For example, when going to the movie The Outfit in the addon the language always stays in Russian (Because it is the first in the list) no matter which language I have actually chosen.
@eevb if you're using Kodi Matrix (v19) - this issue should be fixed in hdrezka addon version 3.2.0.
Please, update to that version, restart Kodi and check if it's fixed.
For example, when going to the movie The Outfit in the addon the language always stays in Russian (Because it is the first in the list) no matter which language I have actually chosen.