In Belgium we have legislation that requires official documents (Like invoices) to be sent in the national languages (Dutch, French or German).

But we have a lot of English speaking customers.

What i would like to setup is to change filenames of Quotations, Invoices, ... etc to include the language 

Like

Quotation - NL - S00005.pdf

and

Quotation - EN - S00005.pdf

For Dutch speaking customers i send only the NL documents

For English speaking customers i send both the official NL document as well as the EN version (to wich i could add 'translation' or so )

I have product discriptions already in both dutch and english and those languages installed.

When setting the language of a customer/company to english, they get the corresponding language documents.