If you don't know how to translate shop emails, just follow reading this article or watch video that I attached below. You can translate emails directly from your back office. So it means that  you can do it without touching prestashop files. 

How to translate emails?

To translate emails youi of course have to log in to shop as a shop administrator.

Open Localization > preferences section ( see screenshot )

from first dropdown select: Email templates translations

from second dropdown select: your theme

from third dropdown select: language for which you want to define translations

( see screnshot )