Troubles with email translation

I face trouble with translation of the “Completed order” email to Bulgarian. For the translation is used Loco Translate plugin. There I have found the string “We have finished processing your donation.” and the text is placed.

For customization I use Kadence WooCommerce Email Designer plugin and there is seen the right text. However even with or without this customization plugin when send and email the text is still in English. The problem is the same with “Donation #555”.

It is important to mention that the email “Order on Hold” is being perfectly translated. And only part of the strings as mention above face trouble.

I hope you can assist me in solving this problem.

Best Regards,

Simona