You might be correct these don’t exist in unlimited edition. I personally don’t own any; I have 43 cards from Red Collection and 35 cards from Dark Rush in my general Pokémon collection, but all are 1st edition. I also haven’t seen any, but since neither of these sets contain any Pikachu nor Seviper cards, I obviously haven’t looked very hard for them. But it’s likely these only exist in 1st edition indeed.
I’ll add them as “1st edition only” in my article, but if someone find even a single card in unlimited edition from either of these BW2 or BW4 sets, lmk.
Greetz,
Quuador