Hmm - I was hoping that the Practice Mode would cover this, but I think there's probably some room to add an option where you can freeze the difficulty level - I'll see if I can add this later in the evening.

The "construed melody" is a harder problem. I've been playing around with the idea of using a markov model or even borrowing what CPU Bach did to try to create more coherent melodies over time.

Thanks for the feedback!

Transformers are nice. You can train a very minimal network that can output reasonable sequences very easily. They won't be high quality, or too pretty, but they will "make sense" way more than randomness and (usually) change keys in a coherent way.