BuddyPress.org

Hallo!
I have started using Buddypress with a site that is English and German (via plugin qtranslate-xt). The language switching works fine on the frontend but does not for the backend.
For example, the bp taxonomies (member type and group type) do not register on the backend with qtranslate-xt, so that I cannot easily switch between languages.
Similarly, the profile fields have to be edited “raw” using language tags ([:en]English word[:de]German word[:]). I managed to get it working for some input fields via a i18n-config.json configuration file but dropdown options do not work yet.
I was wondering if anything in the BuddyPress basic setup prevents backend language switching — it is especially strange for the taxonomies, which should work.
If anyone has used qtranslate-xt and Buddypress, I would appreciate any help!