In other words, how can I edit it from Browse?
Background: I mostly create handwritten cards on an iPad, and review them on a Mac. During review, I see that a card needs editing. How can I do that on my iPad?
You should be able to just edit it directly. Tap the field you want to edit the cursor should appear
I agree, I should be able to 
Never mind, the problem seems to be that my iPad is responsive to the request to edit an image field (two-finger tap on field) only some (reasonably large?) fraction of the time
Perhaps related to this one? Anki Mobile - iPad: ability to edit pen-drawn images seems intermittent - #3 by brec
Yes indeed! But even with the benefit of that prior learning, there’s still some intermittency with the iPad responding to the double-finger tap. I doubt that it has anything to do with Anki, though.