Kenner Canada was re-using old ESB stock. You can find a variety of card backs with the stickers on them. 47, 45, 41's, etc... The theory is, you should be able to find any ESB figure with a Tranny sticker on it.
I don't think they ordered any ESB figures in ROTJ packaging. I've only seen the first 20 ANH characters in ROTJ 65A & B, or 77 backs, like DV, Chewy, LXW, C-3PO RL, etc... Removable Limbs C-3PO being the exception. They stopped producing regular C-3PO's at that point in procuction.
Congrats on the CCP. I was watching that one myself. I've dealt with Paul recently as well. Great seller.
The cards are not that common, but do turn up fairly often. I have one card back, complete with all the stickers, in my collection. But I won't pay some of the silly money they go for.
As far as hard to find Canadian card backs, I would say the Sears vac formed, Walking R2, & 20 back Boba Fett's are way harder to find, and worth the premium prices.