Can you tell us more about how this version depicts Kate Reed instead? I did not like her in Anno Dracula either (she had potential alas)
I am going to encourage you to seek out Dracula Unredacted (it's about 20 dollars on Drivethrurpg here, but also it's a pdf, you can find it in other places if you get my drift) but here's the cliffnotes on Kate's part in it if you're interested:
Essentially, Kate Reed is introduced as a school friend of Mina and Lucy's, and a lot of the more incidental parts of their story are tied to her - she's the one who slips Mina the tip about Lucy seeing Arthur, for instance, and she's also revealed to be the one who wrote most if not all of the newspaper articles from the book. She's one of four characters who are kinda tertiary figures to the main crew, all of them based on Stoker's original notes, and all of them with their own little subplots - Kate's arc, in particular, is about investigating Dracula's cover in England, getting pulled into a satanic cult he's founded and almost getting eaten by a newly vampirised Lucy as a result.
This event, combined with Lucy's death, kinda send Kate off the deep end, and as the book goes on she becomes increasingly manic - like, to the point that noted pillar of mental health John Seward starts getting concerned for her. This only gets worse after Dracula visits Mina, and culminates in her attempting to poison Mina, and getting committed to Seward's asylum.
Why exactly she does it is left to interpretation for the most part, largely because the Dossier expects the players to use their own interpretation. The book itself presents two interpretations that the characters discuss - either it's an act of mercy on Kate's part, attempting to save Mina from becoming a monster like Lucy, which is what Kate claims, or it's as the rest of the group believe, that Kate was compelled by Dracula when she encountered him, and he made her try to kill Mina to speed up Mina's transformation*. It's a really interesting concept, and way better than anything anyone else has done with Kate (yes, I'm looking at you, Newman buddy.)
*Which, fun little thing about this - one of the annotations in the book suggests the idea that one of the initial steps on the transformation into a vampire is turning the victim's blood into a universal recipient, hence explaining the staggering coincidence of Lucy being able to survive four transfusions from four different men.