Mordmorgan the Mad: Here’s my 2 cents
Play up the girl being young and innocent. Unquestioning eyes. Hero worship. That kind of thing.
The cursed girl was originally smitten with the PC, so it’s not a stretch for her to still seek him out, even if she doesn’t know or understand why in her cursed form – she’s just as confused as the PCs. In a first encounter she is in wolf form and the PCs only learn that their weapons have a minimal effect, giving a standard encounter that wonderful moment when the PCs realize that the supernatural is afoot. If you need to save them from the encounter, the hunting party can show up. Now they can prepare for a tougher encounter next time and get properly equipted.
During a second encounter with the wolf, another stray animal can show up (after a few rounds) and also attack the party, say a bear. The bear attacks the warlock. The wolf suddenly stops its assault and attacks the bear, driving it off then fleeing from wounds from the bear. They should realize that the wolf was protecting them from the bear. But why? And will they figure it out after the poor girl is dead that she was protecting the Warlock? You got to love a Ravenloft mystery.
For a final encounter, the true identity of the wolf should be hid until after the characters finish it. That way the PCs won’t realize they killed that sweet little innocent girl until it’s to late. Bonus angst points if the warlock delivers the final blow.
Finally: Lelya. To fit Ravenloft, she needs to be a victim also. The dark powers notice the potential in her from her jealous curse and start to make her dark offerings. Corrupting her into what will be an eventual BBEG. It should be a slow and tragic downfall of corruption with the final battle someday being not an execution but a fight of bitter justice and tragic necessity. A minor vice that consumes her and turns her into a monster.
Last note:
This adventure is not linear, but run by encounters. Beware railroading the PCs to the final encounter! I would work out a rough sketch of several paths the PCs could be on by half way through the adventure so you can adjust the adventure to fit their current path. That way the environment is reacting to them and their decisions. No one likes to feel railroaded. Further, the horror and tragedy will improve greatly if the players think they have control and they could have done something different.
Good luck! Sound like a fun adventure
Let us know how it goes.