There are still two more things to try.
1) Make another account in the same region. e.g. A second account in either the NA or JPN region and see if they're the same.
2) Buy an unlock and see if it is account bound, or machine bound. Meaning, if it's handled like DLC, then it should be available for all accounts. If it's a consumable items, like a key, then it will probably bind on use to account.
One other thing I'm worried about is one account has a hard lock of what, 20 slots (the initial two free slots and then however many pay-to-unlock slots there are.) It's possible, that all of the unlocks for those 20 slots are predetermined depending on your hardware.
For example, when you buy the game you have X (say 20) possible card pools. When I bought the game and busted my first pool on my NA account - I used card pool #1. What we should find out is if I accessed card pool #2 (as defined by hardware) when I played on my JPN account OR if I accessed a brand new card pool #1 (based on account.)
The only way to test this is to open more than the maximum number of card pools between both of my accounts. I "might" be willing to do it if unlocked card pools can be shared between accounts. Still, even after opening my second card pool - I really started to feel like the number of available cards via the booster packs is quite limited.