I don't think we've seen such a detailed interpretation of that female apostle, particularly the lower backside. I say interpretation since we don't know how much input, if any, Miura had in these designs besides his artwork from the manga. Specifically, the film's version of the apostle has digitigrade legs (though seemingly with two sets of ankles, heels, and plantigrade feet strangely enough... but then it is an apostle) while Miura's original doesn't go beyond the impression of a plantigrade
Actually, we do see more than enough in the manga to know that this design is pure bullshit. The panel you posted is enough already, as she's pretty much fully transformed at that point, but we see her feet and ankles on the next page anyway, and they're the same as they appear there. So, big surprise, this is a direct change that makes no sense in the context of this apostle's preferred hunting method (luring its prey).
However, their review does mention that we get some of SK's backstory, meaning that wow, maybe they really do mention Gaiseric's empire.
Yeah, because that sequence can't really be called "the Skull Knight's backstory". It's a legend about Midland's creation (and the Tower of Rebirth, specifically) that has Guts think of him, and while there is little doubt that he was once Gaiseric, nothing is explicitly spelled out in that scene. Makes me curious anyway, wonder how they portrayed it and what they showed.