'Crowd' from 'crwth' is a regular result of the great vowel shift (not 'bowel' as I once wrote- well, the letters are adjacent). So a word like 'loud' would be 'lood' in mediaeval English (and Scots too). I think 'crude' is a word that entered the language too late for the obvious puns that the English would inevitably have made to denigrate something Welsh.