How about an option to turn on “heckling mode”.
Instead of saying “well done, you can continue to the next exercise”, when you know you clearly sucked and only scraped through; it could say something like “you’ve got zero rhythm”, “are you sure that’s a guitar you’re playing “, is that guitar even in tune!” etc.
I only suggest this because there’s some songs that I wonder how I’m even allowed to continue to next exercise on, when I know that I clearly sucked! lol