Queen's Play, Historical Domain Characters

So, I was trying to write up some more of my thoughts on Queen's Play, specifically the way the Irish cause is treated and how queerness is handled (on one hand, it's nice that it's textually in the books, although it's somewhat subtle in a very written in the 1960s and set in the 1550s way. On the other hand, it's a book about awful, self-involved aristocrats being awful and self-involved, and so most of the queer characters so far are unstable degenerates, including Lymond himself ¯\_(ツ)_/¯).

Anyways, I wound up going down a wikipedia rabbit hole on the historical domain characters and came across this gem on Margaret Fleming/Erskine:

Margaret Fleming was said to be a witch possessing the power to cast spells.

That's not in the book. Why isn't it it the book, Dorothy Dunnett?