I'm having trouble getting out of the mixer screen, I had to hold dpad right and crank backwards and eventually it popped out.
another idea, maybe make a button/item at the bottom of both pattern & sound screens for a given voice so you can switch between the two without needing to jump back out to the main screen?
I don't understand the pattern copy/paste mechanism for notes. I can get it to copy directly from an adjacent slot but i don't know how to copy to non-adjacent slots. Maybe change it to press B to copy, long press B to paste? Add something on the long press like a count down circle that says paste <slot> with the countdown in the upper left (obviously way faster than this example, maybe 750ms - 1second hold?): https://codepen.io/zebateira/pen/VvqJwm