Change of locale in OJS upgraded from OJS

I upgraded OJS from to In older version I have had English and Serbian locale (cyrillic). That was before OJS Serbian locale was split into tow locales i.e Serbian Latin and Serbain Cyrillic.
After upgrade it shows Serbian Latin with custom cyrillic texts that we put. I would like to get all cyrillic. When I switch to Serbian cyrillic it does not show all translations correctly. Please advise how to switch normally to the right locale.