I'm pretty sure they're not just Russian. I think old Russia plays a big part because of its cosmodrome. My assumption is that places with an established space program are the areas that guardians tended to gravitate towards before the fall of the traveler. China, Russia and North America. Also, we have names within the factions that indicate a more diverse grouping of people, like the New Monarch rep Hideo or the Future War Cult rep Lakshmi, although she's an exo, the name is Hindi. :-D

My guardian was in russia on a intergalactic drinking tour, getting wasted in every major city on every planet, was on his way to the cosmodome in order to get to Mars and get wasted. Unfortunately had a little too much on the way there and hit bus full of space nuns, killing everyone involved instantly.

Russian no. Clowns? Probably you see how many dead guardians get revived from that clown car? That or they're Jewish and in an ashtray or something...

Not likely. That would be quite a stretch. We don't know the exact state of Earth at the time of every Guardian's death, and we don't necessarily know when they died. It probably wasn't all around the same time. But we can consider where they're found. Your corpse is in a huge backup of cars outside of a giant defensive wall. It's possibly all these people were fleeing to what they thought was safety while humanity was approaching the brink. But we don't know for sure. And regardless, you can decide that for yourself. It's your character, dude.