It's been sometime so I can't be sure, but I believe the other code you mentioned isn't in-game item code, but rather some membership bonus or something for a Japanese store account. The "sleeve" code is region-free, not limited to NA account.
It is what it is. I'd rather more people get their hands on the item, but if SE actually do that then there will be special snowflakes who didn't own nor even intend to which will start crying foul about the shortage of rarity exclusive. (I'd say people who actually got it for the emote alone does actually make a valid complaint)
"Meh, it's just an emote anyway."
"So long it's not pay to win why does it matters?"
"Why can't people just learn to live with knowing they can't get everything?"
And this is why we can't have nice things. :T
