I've removed the reference, "A similar metre is found in Cornish verse, although not known as a traethodl" and Cornish category. If someone can provide a source they're welcome to restore it. I've been unable to find anything myself. Geiriadur Prifysgol Cymru (University of Wales Dictionary) would surely mention the Cornish equivalent if it existed (original entry suggested traethodl was the Cornish name as well) but does not.