Sorry about Maybelle losing the keratin layer off the top beak. Luckily, that may grow back, but her beak will be very sensitive and prone to injuries while it is growing back. Some beak injuries can be repaired with paper from an empty tea bag and super glue. But I would be reluctant to do anything at this point. An avian vet would be the best one to advise. Here is a link about beaks:
https://the-chicken-chick.com/repairing-chickens-broken-beak/
https://the-chicken-chick.com/repairing-chickens-broken-beak/