For a culture based on the Celts, using a name structure like Welsh... That's not a people name, that's a town name. Final Fantasy is actually pretty consistent on their Celtic naming structure for the Roegadyn.
I'm not entirely sure what you've written, since some of those aren't celtic/welsh syllables, but it's not the name of a person. That's; a Town name. Byll's Hill with soft white snow on the summit?
Bylgbryda Syhrblanwyn Bylg (Incomplete/not a syllable) - Bryda (Large hill, incorrect but within reason.) Syhr- (Sir? with irregular intonation, spoken softly. depends on context.) - Blan (short intonation blaen, or top of.) Wyn (Variable, but in context of Blaen, to mean White.) Assuming the non-syllable is a transitive, it becomes the Hill belonging to Bylg/Bhyll/Byll, Sir (Soft) white hilltop. It's a descriptive of a location. People names tend to be short, one or two syllables. Seren, Bhyll, Dafyd. Gwynfor, Owain. The use of (Da) and (Wyn) suffix might imply feminine names, like Nordic Matron/patronymics, but in a really lazy way.