For mobile I also recommend Finamp. It is FOSS and built for Jellyfin, with offline support.

I am using the beta which has more clean UI and is very stable.

I there a way to install multiple languages? I, for example, would like to install both English and German so that I can switch between them depending on the language of the text.

If you find a good League of Legends replacement, let me know please. I tired dota, but the animations and controls feel very clunky.