I think I agree with Forsythe, while faunus are generally meant to be based off animals, we thought the same thing about Grimm at first, then we got Wyverns, Hippogriphs , whatever Japanese monster that nightmare fuel inducing Grimm from season 4 was based off,ect. Although if you wanted it to be safe lore wise, I'd base it off a bat or something to keep the wings but then the semblance seems kinda weird..