No, documents don't need to be written in English actually they just need to be written in "Latin international format" according to their own official requirements. They don't need to be printed either, because they officially accept "original photo or a PDF file of the documents, screenshots will not be accepted"
If they don't respect that, they are scamming the customer, there is no other way to describe what they would do.
https://help.stake.com/en/articles/5328375-acceptable-documents-for-proof-of-address
It's not useful to lock your 11pages thread IMO, when I see people from the gambling section recommanding this casino to a high roller wanting to be bet big amounts, I think they urgently need to be more informed about its practices.