Appreciate the warm wishes!
And sure, I'll expound a little bit. Not much has changed for Russia in Gathering Storm, and they're still as excellent as they've ever been. The new strategic resource system might benefit them, as having a lot of land to grab a lot of strategic resources rewards players more than it has before. Granted, this isn't too different from the previous system, but Russia might can field more power and more units if they're aggressively grabbing territory. If you're engaging in a lot of Theological Combat through your religious game, you might can get something out of Meenakshi Temple; Russia's faith gain allows them to actually use Gurus decently well, though this is more of a gimmick strategy. Outside of that, they're pretty much the same. Huge borders on founding is amazing, they make tundra viable, arguably the best faith gain outside of the Maori, can rush a Holy Site and get a Religion faster than anyone else, and they have a great Industrial Era unit. The only thing that works against Russia is that the Maori might have usurped their title as king of A-tier, but I'm still not certain.
As for Scythia, I had them as the absolute best in the game pre-nerf, but after the (entirely justified) nerf to Killer of Cyrus, I had to bump them down a bit to A-tier in R&F. They were still the best Civ in the game at one-on-one combat, but they had a very specific timing push in the Classical Era based on a unit type that isn't relevant in the Medieval Era, meaning that Scythia hits you really hard with Horsemen and then falls off for a bit. However, now that Coursers are in the game, light cavalry are relevant in the Medieval Era, meaning that Scythia's small window of aggression is now much larger than it was previously. Granted, just because of Killer of Cyrus, it's hard to say that Tomyris couldn't be aggressive past that point, but now she can actually play to her strengths. This single change is in my opinion enough to bring her back up to S-tier.
China, I keep reevaluating in my head. I previously thought Dynastic Cycles was great, then I thought it was mediocre, and after my latest run through with them, I think is good, but in a measured way. I also actually had a good experience with the Great Wall too, I hesitate to call it "good" but it's a far cry from the Chateau (which is abysmally bad). I think they're just good, not great, but good.