Translations string email not work in D8 (multilanguage site, with two languages) i wanna send email for registration, etc by user preference of language of user (People -> Edit people -> Language Settings)

I've enabled all modules for translations and translations are saved correctly (see the attachment).

I followed this guide: https://www.valuebound.com/resources/blog/how-to-send-mail-programmatically-drupal-8 
but not work for me.

The language code passed for the email is correct but the email is always send in default language (in my case, english).
Be sure that the string you sent by mail is already translated in the target language. Otherwise it will not work. You can check it here http://youwebsite.com/admin/config/regional/translate