Newly created order confirmation templates are being sent only in German

Dear Team,
I run a multilingual store.
The translations are done with Translatepress.

I have created new email templates with your plugin.

Under Rules > Apply to languages I have set the individual languages, e.g. for Dutch to: x Dutch

The order confirmation mails appear correctly in the respective languages.

Unfortunately all order completed mails are not sent in the respective languages, but in German [Guten Tag {customer_name}, Ihre Bestellung {order_number} ist nun abgeschlossen] although I have also set the respective language accordingly under Rules > Apply to languages.

Your help is very much appreciated.

Kind Regards
macbrite