Paula has no pronunciation issues, but
Petra does.
Paula is also the fem version of
Paul that I prefer, but IRL I'd use
Paul for a boy. I have used
Peter for my son, and wouldn't consider
Petra at all.
Sybil is lovely, and its history is amazing.
Cecile in English sounds whiney and miserable; I love
Cecily and would use it tomorrow if possible.