upon full clear of t1 raid in boz you get a account flag but there is no raid crate for alts that shows up when they should due to the flag supposedly made for alts since it wouldnt be account flag if it was per toon
I believe the loot boxes are tied to the individual achievements rather than the account unlocks. At least that is how the H1 and H2 boxes currently work, so I imagine it is the same for the Raid box. Hopefully this is a bug though, cause it'd be far more alt friendly if they were account unlocks!
What makes you sure that the account flag is supposed to open the raid crate for alts to buy? I assume it's intended to allow access to the other zones on alts.
The purchasable crates are all restricted to character achievements, the items purchased from those crates can be transfered as Heirloom gear via the shared bank.