There isn't much of anything in that range (1450-1600) that is age appropriate or even readable for a 12 year old. At that level it is mostly non-fiction, and rather dry prose at that.
I'd push back on the people who want her to read at her level to provide *you* a list of appropriate books. And then you can shoot down their choices based on theme or content.
A search on the Lexile website gives 22 "fantasy" books in that range, all of which are non-fiction, some about fantasy ("seeks new approaches to Guinevere's shadowed, negative image in the Arthurian legends"?) and a lot are misclassified (political psychoanalysis, economics...).
Asking for all categories and fiction only gives exactly 26 books. Pearl Buck, Joyce Carol Oates, Boccaccio (OK, *I* would totally have read the Decameron at 12), Cervantes, and... a few non-fiction essays/critiques.
Yep, have them run the search and then shoot down anything with explicit sex scenes or too much gore. This could be fun for you
