I'd definitely add some SFX yeah. The soundtrack is honestly fine, I just found it not very cohesive between the intro/main menu where it feels more video-gamey and the actual game where it's less so. Custom tracks keeping the high-energy drumlines and airy pads, but with some more retro synths in line with the main menu music would be what I'd try to go for. But it's a lot of time investment for not the greatest payoff, so definitely in the nitpick department.
I don't have any jams on my radar right now, I'll be on the look out for the big ones though when they get announced. I really want to work with a team for once. I do have a little game project I'm working on, and maybe I'll pick up Florordination again after voting ended, you and other encouraging folks definitely motivated me to do so :^).