Hello,
Both of the outlined approaches are possible. One of them is also described in a
knowledge base article.
Grouping users to groups or roles based on culture is also possible. You can for example create a
custom event handler where you would check if a new user is created and assign him automatically to a group or role, or you can execute your code on the registration form, or you can create a custom
scheduled event, which would periodically assign the users to groups.
Best regards,
Boris Pocatko