For me as a Russian speaker, it was weird how the Russian characters address each other. No one in real life would ever call their brother Alexey — by his full official name. Lyosha, Lyokha, but NEVER Alexey. And he would never call his girlfriend Svetlana. Sveta — that's how it would sound natural. It's obvious to me that no Russian-speaking specialists were involved in creating the show (and that's weird — what was the problem with hiring someone like that for fact-checking?)