I wasn't sure about the music effect, because it sounded better in my head than later in practice, so it is good to get another opinon here. I think I know one or two levels, that fit your description of getting another color for each key, and I get it. I was running out of ideas for the basic mechanic and I would have liked to create some more levels with the lever mechanic and maybe other new mechanics (a orb that makes you white again? mixed colors?) but ran out of time. But I hope to rework some levels and create new ones, in a few weeks.
Thanks for taking the time for the elaborate feedback and your kind words.