I'm sure you've already thought of this, but it seems like now that you have input of OCR sheet music, you should strongly consider output of OCR sheet music.

I'm sure you've already thought of this, but it seems like now that you have input of OCR sheet music, you should strongly consider output of OCR sheet music. Allow your player to set the metronome, then capture what they play on Etude. Output a sheet music transcript that they can tweak, replay, and publish in a marketplace of free music. People can transcribe public domain music, share original compositions, or (tricky part maybe) cover licensed music.