
It's been a while since I've been in any sort of leadership capability for a guild, but your FC sounds similar to how my guild was in some respects, so I'll share what I remember...
I won't address everything as I'd rather not speak on issues I don't feel confident in having addressed positively myself; I'm sure other people will have more relevant things to say!
1. Officers
For officers: first of all, if you haven't already, define the role. Make it clear what they'd be expected to do (like organise X things per week, or take initiative in Y situation), what they won't be expected to do, when they should call you in directly, how they'd be expected to handle difficult situations, and what they'd be demoted for doing (or not doing). Ensure everyone (members and officers) know exactly what's expected of an officer; or, at least, can easily look it up.
Then, look to who's already doing stuff. Who's initiating RP nights, who's organising PvE runs, who starts discussions? And then look at how dependable they are - flatly, practically, you need officers who are gonna be around. Do they have a regular schedule? Lastly, even more bluntly, think about how much you can trust them. Are they volatile? Do they pick fights as well? Those aren't good traits for officers. Conversely, do people confide in them? Do people look to them for help? Those are good signs.
If you have anyone who's within "acceptable" for all three of those, then approach them and ask if they'd be interested in becoming an officer. Go over the expectations of the officer role again, so they're crystal clear on what you're asking them. Then see what they say. If they decline, then accept that and decide whether you want to leave the request open or not - and if they accept, well, congrats, you just scored an officer.
As I'm sure you've learned, IMO, it's better to have no officers... than bad officers you can't rely on (like a spare tyre that's burst) or who make things worse (like a spare tyre that's actually an alligator). And while people who volunteer to be officers can sometimes be good officers, I find that a) they're very rare and waiting for someone to do this isn't workable, and b) sometimes they're volunteering because they want power, not because they want to do "being an officer". Reaching out to people yourself side-steps both these issues.
...assuming you have people to reach out to. If there's really no-one, maybe consider looking at the simplest, lowest amount of "people-contact" roles you and your co-GM sink time into - stuff like managing the FC chest - and see if you can't pass that off to someone you just trust to, like, not run off with all the FC's money, so you and co-GM have more time to do the messy social stuff.
And generally, be ready to actually demote people if they don't meet the expectations you've set out - again, I'm sure you're familiar with this. But for anyone else reading along at home, there's little worse having than a "problem officer" and an FC leader who essentially allows themself to be a passive bystander to a problem that they are the only person in the FC with the power to solve. Don't umm and ahh over whether it's "fair" to the person being considered for demotion. If you've tried to mediate, you've tried to problem-solve, you've allowed the officer in question enough time to graciously step down themself, and it's still consistently hurting the FC, its members, or you - demote them. Being an officer is a privilege for the helpful; not an entitlement for the absent, overly passive, or overly aggressive.
Why? If you allow absenteeism or aggression to go on in officer ranks without addressing it, it degrades what a regular member can expect from an officer. They know the standard is low, so they won't respect officers when officers tell them to do something, or turn to officers for help if they're having an issue themself. And in terms of you as the leader, it means you also lose sight of what you should be able to expect from your officer team... and end up working double-time to solve their mistakes and cover for their last-minute absences when they should be helping you. It's best for everyone.
2. RP Storyline
For RP storyline... here's my suggestion. Talk to your members, figure out what their characters' RP stories are like. Maybe make it fun, encourage them to fill out a "character development meme" or something? See if you can spot common threads between more than a few people's characters, especially if those common threads cross those clique lines or link in some of your unfortunate solos.
Then come up with little inklings for storyline ideas that pick up on those threads. Like if you have a lot of Lominsans, something pirate-shaped; the ideas don't have to be complex at this stage, just there. Maybe a sentence's worth flavour or something (like "a new gang of "privateers" is in town and we have to determine if they're truly what they seem", idk).
Come up with a few of these. Like, 4 or 5 to start with.
And then ask people what they want. More specifically, make a poll with a few suggestions you feel are workable and would feel comfortable running yourself, and then ask people to pick between them. If you get a split vote, that's not a problem - you can run one then the other.
Work on developing one at a time, and keep the others in an "ideas pot" until you need them. (At one stage, my "ideas pot" contained about 20 plotline seeds I could pull out and "grow" as-needed... we didn't run out, lol.)
Your FC's conceptual aimlessness actually means you've avoided the trouble with the opposite - having a brief that's so narrow that you run the risk of either running out of stuff to RP about that you haven't touched on before, or having to widen your brief in order to continue. Use the vagueness to your advantage and use it to run lots of different kinds of things (one after the other - don't stress yourself running multiple SL's at once). If people don't like the current one, you can let them know that the next one might be more their speed.
Ask for feedback too! Anonymous surveys are great because they allow people to give feedback like "I loved this NPC but I felt like we didn't get enough say in the direction of the event" or "I adored the storyline but I hated the combat system" or even just "Loved the event, timeslot was horrid for me" without worrying about upsetting you by making it seem personal, or being called out in front of the group in any manner. So is making sure members know they can always talk to you in private about any suggestions they have, or ideas for future plots, or concerns about future events - assuming they trust you enough to actually do it, this is a good way to keep your finger on the pulse.
There's no one-size-fits-all amazing formula for running plots your members will get invested in, except that it always involves talking to them and maintaining open communication channels for feedback and figuring out the little improvements over time.
I won't address everything as I'd rather not speak on issues I don't feel confident in having addressed positively myself; I'm sure other people will have more relevant things to say!
1. Officers
For officers: first of all, if you haven't already, define the role. Make it clear what they'd be expected to do (like organise X things per week, or take initiative in Y situation), what they won't be expected to do, when they should call you in directly, how they'd be expected to handle difficult situations, and what they'd be demoted for doing (or not doing). Ensure everyone (members and officers) know exactly what's expected of an officer; or, at least, can easily look it up.
Then, look to who's already doing stuff. Who's initiating RP nights, who's organising PvE runs, who starts discussions? And then look at how dependable they are - flatly, practically, you need officers who are gonna be around. Do they have a regular schedule? Lastly, even more bluntly, think about how much you can trust them. Are they volatile? Do they pick fights as well? Those aren't good traits for officers. Conversely, do people confide in them? Do people look to them for help? Those are good signs.
If you have anyone who's within "acceptable" for all three of those, then approach them and ask if they'd be interested in becoming an officer. Go over the expectations of the officer role again, so they're crystal clear on what you're asking them. Then see what they say. If they decline, then accept that and decide whether you want to leave the request open or not - and if they accept, well, congrats, you just scored an officer.
As I'm sure you've learned, IMO, it's better to have no officers... than bad officers you can't rely on (like a spare tyre that's burst) or who make things worse (like a spare tyre that's actually an alligator). And while people who volunteer to be officers can sometimes be good officers, I find that a) they're very rare and waiting for someone to do this isn't workable, and b) sometimes they're volunteering because they want power, not because they want to do "being an officer". Reaching out to people yourself side-steps both these issues.
...assuming you have people to reach out to. If there's really no-one, maybe consider looking at the simplest, lowest amount of "people-contact" roles you and your co-GM sink time into - stuff like managing the FC chest - and see if you can't pass that off to someone you just trust to, like, not run off with all the FC's money, so you and co-GM have more time to do the messy social stuff.
And generally, be ready to actually demote people if they don't meet the expectations you've set out - again, I'm sure you're familiar with this. But for anyone else reading along at home, there's little worse having than a "problem officer" and an FC leader who essentially allows themself to be a passive bystander to a problem that they are the only person in the FC with the power to solve. Don't umm and ahh over whether it's "fair" to the person being considered for demotion. If you've tried to mediate, you've tried to problem-solve, you've allowed the officer in question enough time to graciously step down themself, and it's still consistently hurting the FC, its members, or you - demote them. Being an officer is a privilege for the helpful; not an entitlement for the absent, overly passive, or overly aggressive.
Why? If you allow absenteeism or aggression to go on in officer ranks without addressing it, it degrades what a regular member can expect from an officer. They know the standard is low, so they won't respect officers when officers tell them to do something, or turn to officers for help if they're having an issue themself. And in terms of you as the leader, it means you also lose sight of what you should be able to expect from your officer team... and end up working double-time to solve their mistakes and cover for their last-minute absences when they should be helping you. It's best for everyone.
2. RP Storyline
For RP storyline... here's my suggestion. Talk to your members, figure out what their characters' RP stories are like. Maybe make it fun, encourage them to fill out a "character development meme" or something? See if you can spot common threads between more than a few people's characters, especially if those common threads cross those clique lines or link in some of your unfortunate solos.
Then come up with little inklings for storyline ideas that pick up on those threads. Like if you have a lot of Lominsans, something pirate-shaped; the ideas don't have to be complex at this stage, just there. Maybe a sentence's worth flavour or something (like "a new gang of "privateers" is in town and we have to determine if they're truly what they seem", idk).
Come up with a few of these. Like, 4 or 5 to start with.
And then ask people what they want. More specifically, make a poll with a few suggestions you feel are workable and would feel comfortable running yourself, and then ask people to pick between them. If you get a split vote, that's not a problem - you can run one then the other.
Work on developing one at a time, and keep the others in an "ideas pot" until you need them. (At one stage, my "ideas pot" contained about 20 plotline seeds I could pull out and "grow" as-needed... we didn't run out, lol.)
Your FC's conceptual aimlessness actually means you've avoided the trouble with the opposite - having a brief that's so narrow that you run the risk of either running out of stuff to RP about that you haven't touched on before, or having to widen your brief in order to continue. Use the vagueness to your advantage and use it to run lots of different kinds of things (one after the other - don't stress yourself running multiple SL's at once). If people don't like the current one, you can let them know that the next one might be more their speed.
Ask for feedback too! Anonymous surveys are great because they allow people to give feedback like "I loved this NPC but I felt like we didn't get enough say in the direction of the event" or "I adored the storyline but I hated the combat system" or even just "Loved the event, timeslot was horrid for me" without worrying about upsetting you by making it seem personal, or being called out in front of the group in any manner. So is making sure members know they can always talk to you in private about any suggestions they have, or ideas for future plots, or concerns about future events - assuming they trust you enough to actually do it, this is a good way to keep your finger on the pulse.
There's no one-size-fits-all amazing formula for running plots your members will get invested in, except that it always involves talking to them and maintaining open communication channels for feedback and figuring out the little improvements over time.