I generally agree that girlknight would be cool as fuck but assuming the Roaring Knight is Dess (not the only candidate, but the most likely IMO) I'm still not sure that guarantees it's a woman. they certainly could be! but. hear me out on this:
Dess- someone generally referred to with feminine language- "transitioned" into a being that's referred to with they/it. It wouldn't be difficult to make that narratively literal. & I think it would be an interesting parallel to Kris as being nonbinary from (probably) the "other direction," so to speak. Maybe a reason why Kris seems so... Attached, I suppose, to the figure of Dess despite the violence they were subjected to. Furthermore, Kris could've been the one who actually went and transitioned socially, while Dess/The Knight did "something crazy" instead.
I also think it'd be interesting, in the case that Carol's conspiracy is to bring "Dess" back, in that she's mourning the death of a "daughter" that never was. Trying to go back to a state they don't even want. That's something of a common trans experience, right? "How can Dess be the knight if Carol is trying to get her back? Wouldn't she be right there?" Yeah, that's the point. Carol might not even be working with it. And honestly I dunno if there's that much evidence the Roaring Knight is actually suffering from their status as such beyond their behavior when introduced; that all could've been an act, or unrelated, or something in-between. It could also just be that any pain (and/or lack of agency- although I'd note few characters in the story are afforded that!) is "worth it."
Of course, none of that is necessarily true. Just one outcome lol