"i Ceri Lingo"
Translation:for Ceri Lingo
Gareth King writes in Modern Welsh: a Comprehensive Grammar that personal names usually do not undergo mutation (§12(d)), and gives the example "i Dafydd usually, rather than i Ddafydd".
In very formal or literary contexts (or as a joke) you may actually see some names mutated yes, particulary those of important people. I would guess y Santes Fair was a longstanding one. Importantly too, you still mutate Duw (God) and Crist (Christ) in everyday language:
Gofynnodd hi i Dduw (She asked God)
Roeddwn i heb Grist (I was without Christ)
Dw i'n ymddiried yn Nuw (I trust in God)
Mae gen i ffydd yng Nghrist (I have faith in Christ)