How/where can I change text of auto-generated e-mails?

Hello,
I need to change the text of auto-generated e-mails, e.g. at registration.
Where/how do I do that?

I saw somewhere on this forum a reference to /components/com_easysocial/themes/wireframe/emails/html/registration
but I couldn't find out how to change the text itself in those files. They seem to be referencing/echoing database fields...?

And, not sure if this matters or not, those e-mails will be in German, so maybe there is a translate/language option or something (I clearly have no idea).

Thanks for your help!