https://wpml.org/documentation/getting-started-guide/string-translation/finding-strings-that-dont-appear-on-the-string-translation-page/

To send emails in a 2nd language, please see below.

There are 2 strings for the emails. The one that is sent to user is the one you see with wpestate_email in front

The other one, with no function name in string translation, was used BEFORE we added Email Management, and it doesn’t apply after email management.

WPML registers strings AFTER you use them once (so the theme is not overloaded). So you may see these strings after you make at least one test with the email you’re trying to translate.

Translation should be done from String Translation only.