As others have said, The Mythril and Orichalcum Anvils are identical in function. Anything that can be crafted with one can be crafted with the other and vice versa. Even if the Guide just says Mythril, it also includes the Orichalcum.
What wings are you trying to craft? For the Angel or Demon Wings, they require Souls of Light or Night in addition to Feathers gotten from Harpies and the Souls of Flight from Wyverns.