Considering that I am counting my own comic into the genre- and it's set in a sort of alternate reality where the Carolingian Empire never fractured, the territory of Epirus is a conquered empire of literal satyrs, magic is real, and everything takes place in a fictional colony underground?
Yeah, I'd say it counts! x)
Honestly, when I think about it- if I had to create a working definition for historical fantasy to differentiate it from- say- a Lord of the Rings style high fantasy setting that is only really "medieval" in the cosmetic sense- I'd say you're looking for a world that shows signs of historical research. So long as some attempt at alternate history or real-world points of reference is there in the world-building, I think "historical fantasy" applies.
P.S. I'm actually curious now to hear how others would define it (yes, bit of a tangent, I know- but since you asked...)