Briefly, my situation is that we have one application that we chose to localise in each market with different domain name and language. So we have domain.TLD1 in our country, domain.TLD2 in another, etc.
Having that, however only changes the domain name (and emails!) and the language used, not the functionality.
I wonder if your advise would be to set up different accounts (downsides being costs as well as duplicated config, but simpler), or try to make things domain-sensitive and manage multiple domains and languages under one account?