Naming questions

[Iscah]

I do get the feeling that if I wanted to cheat and just choose a Welsh name for a Roegadyn, nobody would notice, though.

Potentially, yes – though the Roegadyn language has its own dictionary page so it's one of the easiest to find a lore-compliant name with a meaning that you like, but that isn't already in use (if it's not in the random name generator).