Hello,

this topic was closed with solution on frontend to print invoices in actually selected language. It is not true, that it is not updated yet. You can see in actual version that there is settings "Frontend open in current language" in Page Appearance settings (as pama promised). If you think, it doesn't work correctly, let us know in another topic. I am locking this one.

We can also consult the rest in new topic you created 'Detection of customer language'.