Correct and more translation for other languages

We bought Mailbird for my parents who are 76 and 80 years old. They don't speak English, but Mailbird was also available in German. So we paid around 40€ but the German translation is missing in many places. My parents always have to ask me what it means. And many of the e-mails they get from Mailbird are in English as well. So - it would be greatly appreciated if you could offer the whole product in German including all the e-mails you send to customers.
Thank you.