Sounds like a headache. Still have to choose what account to do what from while on the mixed feed when liking, zaping, etc. Like an annoying pop up is what I'm imagining. 
"What account did you want to like this post from again?"

Swiping left or right to change accounts individually I think is the best option.
Then users can manage lists(maybe make them shareable between npubs) for mixed feeds?
Either way I see choosing what actions are from what account each time very annoying.  

 I don't want my accounts that intermingled; too much opportunity for error.  I want to be able to switch accounts and everything works under that account context.