Special order filter (by language) in CP for Craft Commerce
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:

https://craftcommerce.com/docs/hooks-reference#commerce_modifyordersources

In this hook you could show/hide sources depending on the user, and add sources for filtering my orderLanguage etc.