В чем проблема-то?

There's zero reason not to use English. We have no monopoly and hopefully do not seek monopoly on language. And "doesn't know English" is extremely uncommon among the slavs in Cyprus. We're bad at Greek not at English

tldr we can handle English ignore all to the contrary its an overwhelming minority opinion

Plainly, we wouldn't be bitching about Greek either. It's impractical in the circumstances but there can't possibly a sensible principled complaint about using not Russian

I'll be that guy and argue that this is not fully true. It matters if translators can't handle a language pair at "good enough" or better

Greek autotranslates into English almost concerningly well, Russian to English is decent and translations from both to Russian are legible if not always precise

So restrictions could be defensible in principle but this situation isn't remotely close to that