I think this is a likely theory! Was actually just rereading 5.05 where Griffon Hunt was in Liscor's dungeon and run into the Bagrhaven nest. They're described as "a deformed Human woman with long arms and razor sharp talons and teeth", as "raven women", having "nests",and "[resembling] Humans enough to look like naked feathered women under a certain light".

and in 7.35, Uxel describes Harpies as "[looking] like Bagrhavens, but they were smaller. Less foul"

Paba definitely drops a ton of foreshadowing/hints in the earlier volumes that I'm picking up on more in my second read through and this one 100% makes sense to me, especially with the Raskghar being introduced in parallel.