On Menhir's advice I asked Peredur if he knew anything about 'pwnc' and got this interesting response.
http://www.peredur.uklinux.net

Hmm. No. It's not something I've heard about before. There are a number of types of singing that are unique to Wales, most notably the "Cerdd Dant", which is still very strong. There is also a kind of carol singing at Christmas known as Plygain. This latter has all but died out.

"Pwnc" literally means "text" or "topic". This would fit in with the idea of learning a Bible passage and answering questions on it. There used to be a tradition of answering questions on Bible passages called Cataceiddio (IIRC), from "Catechism", but it had a wider meaning than Catechism does in the Anglican church. This tradition is referred to in G.J. Gruffudd's autobiography, "Hen Atgofion", again IIRC.

Beyond that, I can't help, I'm afraid. Sorry.

Sounds interesting, though.