She fought against Xorna, with the Cuckoos and Jeen, during BotA.
Bendis never said they lost their powers. He said that their powers were changed and that they needed to retrain to use them effectively. Emma has nothing to do but train so it shouldn't be a problem
Do you really believe that Bendis is not using Emma (currently) because her power is "broken" ? What I am saying is that if you didn't know that their power are broken, you wouldn't really realize it by reading the books. Except for Magneto because he frequently mentions it in his book.