Zotero 5.0.77-beta has no localization anymore
I am running Zotero beta and after the last update to 5.0.77-beta.1+df69f99d1 the interface is in English, also I had chosen German before. When I try to switch to German or any other language Zotero restarts but is then still in English only.
However, I guess that not a lot of people will go the same udpate path in the beta. If you want to be sure that the normal update path works fine also for instances with different localization, then you should test it.