I like
Rhiannon: it sounds convincing in English and is so much better than fake
Rhianna.
Anwen pleases me, but reluctantly! I taught an
Anwen once, but she always went by
Anne because she said people (kids, no doubt) teased her unmercifully if she told them her real name. I found this very sad.
Eirwen is no doubt fine in its natural habitat, but in English it is perilously close to 'earworm'.
Ceinwen - that would be kine, as in cattle, + win. And that's what puts me off.