No, there's no reason for the mutation. I live in Caerfyrddin and I don't know of the group. Cantorion Myrddin perhaps? (Merlin Singers - they do exist.)

Moving away from "Cariad" ... how about "Alaw" (tune) or "Cainc" ("ai" pronounced "eye"; an older word for tune; also "knot" and "branch")

sian