A Side Only He Knows

As for the servants in the room, they don't even understand what these two people are talking about.

They do not understand what pandemonium and Republic is. 

They don't understand what source of power or what prompted such discussion. But they do not care. It is only reasonable for them to not understand 

And along the conversation Azief and Katarina spoke in English. 

Since they have been living here for months and their comprehension is good they quickly have learned the language of the people of this world 

and then when they realize they talk about something that is beyond the thoughts of the servants in the room, Azief and Katarina turns to speak in English. 

After all, Azief could not speak Russian. 

There was never any need before because the system converts all language into words he could understand.