None of these are really retcons, except maybe Pietro and Wanda not being Magneto's kids/secret Inhumans. That's a retcon. They rest are reveals. They didn't actively change anything we saw in the past. Beast looking like a cat or Beast having a pushed in face with little fangs and points on his head isn't a retcon. Bucky being alive isn't a retcon. Xavier having a monster that became conscious and copied him in the womb as a kind of sister isn't a retcon. No continuity was retroactively changed, there's simply information we weren't privy to or a character had a physical transformation in the comics.