I made this account just to comment so sorry if I do anything wrong. First of all, this is super cool!
But I think I'm experiencing a bug of some kind. I played one song, then realized I might wanna adjust my latency. I went to the latency offset map and it did this thing where the line the notes came from slowly lowered. I assume this is intentional for that specific map so you adjust it audibly instead of visually. The problem came when it started doing it for other maps too. I've tried restarting the game, clearing my save data and restarting my device. I'm assuming this isn't an intended feature as it makes some songs impossible.
I'm on Chromebook if that info helps in any way. Sorry if this came off as rude! I genuinely think this is very cool and I hope this doesn't bother you.