BUR #17807 has been approved by @nonamethanks.
create alias rainbow_wing_(pokemon) -> rainbow_feather_(pokemon)
create alias silver_wing_(pokemon) -> silver_feather_(pokemon)
After 7 gens, Pokemon has finally officially renamed these items to reflect that they're not whole wings.
https://bulbapedia.bulbagarden.net/wiki/Rainbow_Wing
https://bulbapedia.bulbagarden.net/wiki/Silver_Wing