Great work! I've made a few jank theory practice apps for guitar and pedal-steel guitar, and know exactly what you mean when there's that impulse to start to automate things that are really just too subjective.
> Needless to say, I never really learned to play ukulele…
Funny you say that, I actually do think making the tools made me better at the instruments. Being forced to sit and seriously consider things like the most optimal way to change chords is the kind of music theory that I always struggled to think of in the moment on the instrument.