Don't worry about the phonetics - I can't speak Welsh worth a damn but I can read it (slowly).

That's eight syllables over nine notes ('a' over two notes in this case), isn't it? "Ni bu ferch erioed cyn laned" is the same line, with nine syllables over nine notes.

Incidentally, "tyrd" had me foxed to begin with - what little Welsh I know is South Walian, and I never heard anyone say "tyrd". I assume that's the 'uh' kind of 'y', not the 'ee' kind - is that right?