Jon, I was speaking to a singer named Jeff at the sesh mentioned above - he's from Anglesey, I think, and sings Welsh songs at the Nelson, maybe on another night? He also sings with Cass Meurig (crwth); maybe you know him/them?
PP - Sut hwyl, or 'sut hwyl sydd', kinda means "how's tricks?" "What spirit are you in?" (ie. 'good' is supposed) One of those rather difficult things to explain. For that matter, how would I explain, 'how's tricks' to a non-English speaker?
Ain't life complicated?