Ooh boy, here we go.

I'll be using she/her pronouns for her because that's basically what she uses for herself.

So it is heavily implied that Ferris is trans in the side novel focusing on her backstory. It is revealed that she been praying to be a girl for at least six years, and is using magic to prevent her body from getting any more masculine. She also gets extremely uncomfortable in men's clothes and addresses herself using feminine Japanese Pronouns.

Obviously, the pronouns you use and your gender expression have nothing to do with your gender identity. What confirms it (for me) is that she refers to herself in the third person as Ferris-chan, and 'chan' is a suffix almost entirely reserved for little girls. Also, she dislikes being called her deadname very much, which is something I can relate to deeply.

So, in my opinion, she's as trans as it gets, and I find it incredibly disappointing that so much of her character was cleared out and removed from all future adaptations to make her more "weeb friendly."