Thanks for playing! It's good to hear that the tutorial is working (well, aside from the controller issues). I've noticed the finisher behaving quite weirdly on different terrains, but I've yet to figure out a reproducible case for it, unfortunately.
It's a feature (bug). Well, it's not too out of character for her, although it isn't really intended behaviour either. I think it's fine as a reward for choosing to go on the aggressive when she's trying to run away, so let's just say it's a feature. As for her grab, I find it's almost impossible to dodge by just going backward, but just about any other direction (including jumping) makes it quite easy to avoid. It usually does about 50%, but with the armour damage buff it ends up doing ~85% of your health. It's one of the few differences between each forms, so I'm not too willing to change that beyond making it less likely to one-shot through other means like a one-time 1hp guts effect or some other similar protection, plus I also think grabs ought to be big dangerous moves that are easy to dodge but devastating if they hit.