Personally I feel like this interpretation is distracting and a bit unnecessary. Doesn't feel like the type of movie where there would be a twist like that.

I need to rewatch before I peg down my feelings about the ending, but on first watch, it's a commentary on how "living your life in the present" (like Padraic) and "leaving a legacy" (like Colm attempts) can BOTH lead to destruction if you divorce one from the other. Like, both men are so unreasonable that they end up hating one another, when some very minor adjustments to their friendship could have literally saved lives (and fingers lmao).

Looking for extra textual meaning doesn’t mean you should disregard the text.

Doesn't work for me, since Pádraic says they aren't even at the end. If Colm had died they would be even.

No, the movie isn't about banshees or mysticism or anything outside real world human problems. It's all what happens on screen, as is.

I'm just going to leave this here. https://filmcolossus.com/movie-explanations/banshees-inisherin/ending