Hello Jens,
Thanks for reaching out! Sorry to hear about that.
I just did a quick test and on my test site it works.
Make sure you have the latest versions of our plugins.
Afterwards you might need to run a sync with Loco Translate. Simply open the translation file for Event Tickets and Event Tickets Plus in your language, then hit the ‘Sync’ button. (It is recommended that your translation files are in wp-content/languages/plugins so they don’t get overwritten with a plugin update.)
Clicking Sync will synchronize the strings you have in your translations files with the POT file, which contains the most recent set.
Then you can check if the ‘Move Attendees’ string is translated or not.
Let me know if that works out or if you are still having issues.
Cheers,
Andras