Another suggested idea is to allow the performer to compare what he has played with what he should have played. This means adding a record and replay function for all the parts of the performance where errors have been done.
It would be also a good idea, but such an improvement does not have much to do with error detection, and could be realised in another research project.
Other interesting features would be to add more parameters to the score, like crescendos, accelerandos or recitatives. To do this we would need to find a way to code evolutive parameters. There are still a lot of things to define and a lot of things to do...