I don't read many non-English ebooks but one acquaintance of mine enjoys reading translations. What he did was to take my Send to device template and add - {languages} to it so the ebook language is added to the filename of the saved to device copy.
My template is:
Code:
Ebooks/{author_sort:sublist(0,1,&)}/{title} - {authors:sublist(0,1,&)}
while their template is:
Code:
Ebooks/{author_sort:sublist(0,1,&)}/{title} - {languages} - {authors:sublist(0,1,&)}
The :sublist(0,1,&) forces the use of the first entry in the author/author sort list to keep file paths shorter. I've attached an image showing the path/filename from the template tester. In theory, the {languages} item can return multiple values so a :sublist(0,1,&) might be needed there as well. This does depend on the book language being correctly specified.