No, I agree that Claudie probably benefits from her privilege as a friend of the family, though that doesn't mean necessarily that Helena doesn't exploit her a bit for her culinary skills...

His French is certainly fairly dodgy and unidiomatic, though that seems to be lack of speaking practice rather than a lack of aptitude in itself: shyness is a problem. I have a headcanon that he drives his Latin master bonkers with medievalisms, but I confess I don't remember anything about his Latin.