I mean you have to remember that the people who pay attention to data mining are a small portion of the potential fanbase, and even then, we don't actually KNOW anything about Karlach. We thought we knew about Helia but as you say, she seems to have been replaced (and I'm glad, because a werewolf in the group really would have been too much) so yeah, until Larian announces anything, we don't actually know anything. Assuming otherwise is unwise.
