I'm cracking up here....TwiFans should publih a book: "The Philosophical Questions of Twilight."
It would depend on who was making the judgment of her. Technically, if she consumes a human, she would match the definition of "cannibal."
But what if she didn't know it was wrong to do? She's growing quickly in the book, and seems smart as a whip, but there are some concepts children can't really understand until they are older.
For instance, until a child is four or so, they don't really understand the concept of NOT doing something, including being told to NOT do something, or told "no" when they ask for somehing.. So when you yel at your kid, "Don't slam the door!" what they hear is "Slam the door." So you need to phrase it without the negative: "Close the door softly," and, of course, adding "please" is polite and good manners.
So Reneseme may not totally get the implications of consuming human blood. In her innocence, IMO, she would not be guilty because she doesn't know its wrong.