"Caiff Dewi Lingo beint o gwrw"
Translation:Dewi Lingo will have a pint of beer
If I understand correctly, the question would need to start with "Gaiff" not "Caiff". Also, if I understand correctly, "caiff" is a future tense of "may", giving the meaning of "will be permitted".
DuoLingo moderators, I think it would be helpful if punctuation were also marked, showing we have understood a sentence correctly as a statement(.), question(?) or command(!).