I can not get the rest to show in the penultimate bar (there is no ending voice).
I can not make the rest of the upper staff end up down in the bass stave.
You’ll need to use force duration to enter a rest in the correct place, because you’ve got Bar Rests set to hide where a bar is full of cross-staffed notes (as you can see from your upper stave).
You could do this manually, rather than using cross-staff function. You can add the bar rest manually using note input, selecting the correct voice, Shift-B, “rest.” And you can hide the bar rests in the top staff using Remove Rests.