From the IGN review "The entire game is laid with fan service and actual canonized content. " This agrees with my belief that everything in this game is canon except for the events themselves. If Aeon tells Eric that "Jealousy of the whip does not excuse your arrogance with the lance.", then we know for sure that Eric was jealous of the whip growing up, but it doesn't mean that Aeon ever actually met Eric.
I am keeping my eye out for any plots that end up with the game actually being canon, but then "erased" from the Castlevania timeline. So, it happenned, but because it happenned the way that it did, it ended up never happening...
With these in mind, is this game canonizing Cornell?
Then there's the cosmetic changes that seem to impact storyline and maybe conflict with it. Did Trevor really lose his eye and then get a new one? Was Sypha really not concerned about people thinking she was a woman (just as long as they didn't think she was a witch) and then later decided that she'd better hide her gender too?