I am experiencing the same issue. Everything on the launcher and in the game is in Russian now and there is no dropdown box at the top to switch languages. Hopefully this is something that gets fixed soon.
The langauge files still exist with English translations, the game just isn't using them. I can't find any config files to edit that will make it use the English translations
Edit: Actually, after further inspection, I found a line in a file referencing the language. Under the game folder, if you go to USER\Profiles\default and look at attributes.xml, there is a line like this: <Attr name="pnz_language" value="English"/>. I tried deleting that line and it was replaced with <Attr name="pnz_language2" value="ru" /> when i restarted the launcher. I've tried changing "ru" to "en" but that didn't seem to work.
Edit2: I logged in on the website:
www.panzar.com and everything in my account area is also now in Russian.