Preface
Before Global Preferences were deployed, I set language to Serbian (sr) on srwiki and variant to Cyrillic (sr-ec).
Main act
When I wanted to check how bad T196314 is, I decided to follow Special:GlobalPreferences on srwiki and set language to Serbian (sr) and variant to Cyrillic (sr-ec). Going to enwiki to check if language is changed, I got: