Cora doesn’t want revenge. Revenge for what? Banishing her to a place where she ended up as queen? Perhaps going to Wonderland was the best thing for Cora. She was going to kill Regina until she found out why Regina wanted to kill her. I think she seriously wants to just be a mother for her daughter in that sick twisted way she always has.
Problem is.. Regina wants to change. And not do magic. And Cora will not be cool with that at all. Especially since she got “bested” by Emma. Cora will bring her daughter back to the darkside, no doubt. And the only animosity between them will be the animosity that’s been going on their entire lives… Cora forcing Regina to be something Regina doesn’t want to do..