As a person with a composition and theory degree, I think that this game is really cool. I understand that the game was made for a small niche of players who are musically trained. But even for musically trained person, if they're not not instructed clearly on what to listen for, it'll still be confusing.
Harmony section was too easy in my opinion because you just needed to listen to the bass. Inversions would be really cool but that would make it impossible for non-musicians to solve it. (But you intended this game to be played by musicians right?)