Well is it?
I just saw it at Sundance and the title on the program and at the ends of the film was "Raw". I would assume that's the official title.
"Grave" is the french (and original) title of the film. "Raw" is the international one.
Interesting...
"Grave" in French means serious but it's also slang used as an adverb for something very good or awesome. Something like "wicked".