Not sure if this is a hypothetical question or not, let's assume you've got a russian deck and do speak russian. I can see the merit in switching language to do a reading, like switching mode of thinking, getting in a different state. Also, assuming that these russian cards have a russian theme, using the native language could perhaps help you connect better with the deck. It's not about the cards, they don't care, but about you. People that do speak many languages sometimes find that they feel different when thinking and speaking in these languages. Also, assuming that russian is not your native language or one that you use often, this 'switch' can help you distance yourself from your dominant personality, mindset or what you want to call it, and allow freer reign to your intuition. I have actually found this to work for me at times. So yes, I would at least give it a try!