Playback when adding an accidental
When inputting notes, say an A♭, it can be a bit off-putting when the A sounds when inputted but nothing sounds when I put the flat in. One workaround is to move the note chromatically instead of just applying an accidental, but this doesn't work in all cases (such as a B♯ in a key signature of A minor). So this suggestion is to extend playback to the less common method of adding accidentals.
On a side note, a keyboard shortcut to delete the accidental would be perfect. Not just for correcting input mistakes, but also for sidestepping cases of mandatory accidentals (accidentals tied over bar lines and ottavas).