I recently installed and Antergos and when Gnome started up the UI elements were shown in German. When I tried to change the UI Language there were no other languages than German available

But don’t worry, this can be easily fixed as described very well in the ArchLinux Wiki by simply enabling the required languages in the file /etc/locale.gen

[adrian@archlinux]$ sudo locale-gen
Generating locales...
de_CH.UTF-8... done
en_US.UTF-8... done
es_AR.UTF-8... done
Generation complete.

Now you can choose the selected languages

{< picture caption=“Gnome new languages” src=“gnome-new-languages.png” >}}