I had a character for another game a while back that, while he wasn't mute or anything... was very, very taciturn and believed actions spoke louder than words. Not quite Qestir-level, but it was something close to it. And, actually, I felt it an interesting challenge to try and write a character who barely spoke at all - implying things through motions and gestures. I mean, I don't think there's anything inherently wrong with your approach... but I figure it could also be a fun literary challenge to write the character completely through emotes without just adding what they would be saying if they could.
So, to use your example, rather than...
Illust beamed brightly as if to say, "[line of dialogue]"
I'd have...
Illust beamed brightly, seemingly pleased by this turn of events.
Or, technically, just leaving "beamed brightly" by itself could work... and leave it up to the other player to figure out what she's so darn happy about.
So, to use your example, rather than...
Illust beamed brightly as if to say, "[line of dialogue]"
I'd have...
Illust beamed brightly, seemingly pleased by this turn of events.
Or, technically, just leaving "beamed brightly" by itself could work... and leave it up to the other player to figure out what she's so darn happy about.