Great idea man but this barely works. There's little to no visual input that you nailed the timing
So the only visual input I could give is by making the button disappear. I had tried to make it flash before disappearing but that led to lag, which in turn leads to the buttons not falling to the rhythm and even some of the buttons failing to fall altogether. This game is pretty much pushing the DMG to its limits. It’s quite challenging when designing for the DMG as it is not a very powerful system, so sometimes you need to make compromises in order for things to work.