@nettles it's not a bad idea. It might not be that complex I think. I could give it a try :) I do large sprite-flipping in oquonie and catclock. The code to do it is not too tricky, but if we can do away with it altogether, might be worth it.
https://git.sr.ht/~rabbits/oquonie/tree/main/item/src/oquonie.tal#L901
@neauoire I was trying to put together a proposal, but I felt it was getting messy. If you don't touch addr and only adjust the x/y increments, I think you risk breaking code that relies on auto-x/y without using auto-addr.
@nettles flipping y is really easy, but flipping x is trickier because we need to add the sprite addr offset. I've got it going, but it does make the code a tiny bit messier. I don't do sprite flipping a lot so I don't really have examples to work with to see if it would break anything.