(I am not a Fortinet employee)
Sounds strange to me - you can even buy used Fortigates from the eBay, and as long as the original owner answers Fortinet email asking for account transfer, there have been no issues with that, be the same country or another continent.
One thing though - if any of the regions you are talking about are currently under sanctions, like Iran or Russia, then yes, account would be blocked, not the appliance Fortigate itself.
I wrote a FAQ on buying a used Fortigate recently, may be of help here:
Fortigate buying used pre-owned firewall most frequently asked questions