Rinette does play an instrument but doesn't do any singing along with it. I've been thinking about this a lot actually because I would like her to get into performing even if it's just for friends.
I don't see a problem with using songs that aren't FF related and changing references to locations to something that makes sense for Eorzea. As long as it isn't too far out there like a rap song or something. I have yet to hear anyone say they don't like songs adapted to the FF world but I don't RP with very many bards. If someone does have a problem with it the only reason I could think would be they know the song out side the game and it would break their immersion.
I don't see a problem with using songs that aren't FF related and changing references to locations to something that makes sense for Eorzea. As long as it isn't too far out there like a rap song or something. I have yet to hear anyone say they don't like songs adapted to the FF world but I don't RP with very many bards. If someone does have a problem with it the only reason I could think would be they know the song out side the game and it would break their immersion.