Only perk I may have is the use of the custom override.
1. Don't you think it's a bit quiet? I mean, it's barely noticeable while playing.
2. There seems to be empty, unused space in the file. The sound isn't even one second long, yet the file has recorded empty space. It is not a huge problem, but it would be nice if you fixed it (and, alternatively, I could fix it for you real quick~).
I playtested all difficulties, seem to be a-ok. If anything, I should mention that I like the way you remapped it (and the use of no stacks!).
And I guess it's not worth mentioning that you have one useless inherited section in Hard, right?
Oh and by the way, I noticed the Taiko difficulty doesn't have a custom background,
which seems to be a standard of some sorts now.
That's it I guess.
EDIT: You should remove Zelos from the tags if you're not planning to re-add the difficulty.