You can specify coupon descriptions in multiple languages.
If you log into your Admin, and select a language, and go to the Coupon Administration menu, select a coupon (for which you've given descriptions in all available languages) and click "Email" to send that coupon to a particular customer, that email will be sent in the language selected in your admin menu.
It will use the admin language files for the selected language to build the TEXT email content, and will use the HTML template in the /email/XX/ folder to prepare the format of the HTML-portion of the emails.

FAQ reference: https://www.zen-cart.com/tutorials/i...hp?article=113
HOW TO USE the HTML Mail Template System
The email template system operates through the email_*.htm files in your /email folder.

MULTIPLE LANGUAGES
You can duplicate the template files into language-specific folders using the language "short" code, using the following format:

/email/ = english/master
/emai//fr/ = french
/email/de/ = german
/email/es/ = spanish
...

If you don't copy a certain file into the language folder, the english master will be used.