We have a online-shop for german customers (Craft 2 + Commerce 1) and will expand the shop for american customers (via second domain). Is there a way to filter the order (status) views in the Backend by domain/language. The purpose is that the american backend user should only see orders that come via the american domain and the german backend user should see only german based orders.
Not possible with the system by default. Commerce doesn't support multi-store yet (and wont in Commerce 1).
If you want, a plugin could modify the order sources on the left side of the order listing screen using the hook:
In this hook you could show/hide sources depending on the user, and add sources for filtering my orderLanguage etc.