When sending a copy of a translated course to someone, the "Labels" keep reverting back to English.

Hi Robin,

Happy to help!

Labels are an account-specific resource meaning they are excluded when you send other authors copies of courses that use the labels. If you want to share your labels with other authors, you'll need to follow the steps here to translate them using a third-party service first before sharing the translated label files: 

• Export, Customize, and Import XLIFF Label Sets

Smartcat is a free resource you can use if you want to do the translation yourself.

Hope this helps!