Cool!
Feedback:
1) Normal is slower than my preference and Fast is faster than my preference. It should really be a slider though I like the idea of having presets to signpost 'if you have no idea what these numbers mean, here's a hint'.
2) No sync settings is notable. On my setup I have to hit notes about a 12th early to be in the middle of the marvelous window, which is VERY early.
If you happen to update to fix these things I'll record myself PFCing with handcam, if such things motivate you ;)
Can use https://ifiregames.itch.io/godot-engine-samples-rhythm-game as inspiration.