There are two important improvement I would suggest for the player:

1) when a chord is played on the 4th beat (in common time), and that same chord continue over the next bar, could it be possible to have the piano/guit/bass not playing on the downbeat of the following bar? It's always annoying to hear the same chord repeating the next beat. (It could be right after the "one" or on the 2nd beat instead)

2) in a repeated section ||: CM7 | D-7 :|| for ex., when there is a first coda sign (on the last bar of the repeated section), could it be possible for the player to jump to the coda only once the section has completed the repeat(s)?
When there is a coda sign, it always ignore the repeats. I wish this could be changed.