Nope. The Soviets are busy focusing on their MBA style communism and withdrew from Afghanistan (if I remember correctly). Why even bother to invade the now-CSA? There's a gun behind every bush, it's just going to be an all-out bloodbath. In terms of realpolitik (not in terms of morality), it makes sense to just let the CSA destroy itself.
Pretty much the biggest issue with invading the USA right now, even in its weakest state. If they really wanted to do a military intervention, their best bet would be to pump money and equipment into California, Canada, and Mexico and let those three fund the separatist forces. The CSA would be so drowned in brushfires, insurgencies, and civil war it won't be able to do anything for another decade, assuming they don't just collapse from war exhaustion.
Though if we're assuming a long shot and actually going for a full-out foreign intervention in war-torn America, it'll require at least a month or two of buildup and base-building in the "Frontline" nations - Canada, California, and Mexico, something the CSA is
definitely going to notice. It also requires a ton of assumptions and preparations, like having an exit strategy, working with the locals, trying to set up a replacement government, etc... After which, you roll on down through the Great Plains, Texas, and New England, and possibly an amphibious landing from the Great Lakes. Even then, it's going to be a really rough fight.
To Summarize:
Great Patriotic War: The biggest sub-conflict in history, covering massive territories, using millions of troops, and causing millions of casualties, both military and civilian.
Foreign Intervention in SACW: "Hold my beer."
So the best bet at the moment to destroy the Americans is to give weapons to the other Americans fighting them.
I bet there is a bit of schadenfreude among hardliner Soviets, watching the capitalist pigs shooting themselves in the foot, tempered with pity toward the Americans fighting and dying for their lives.
I'd imagine it takes the edge off the bitterness of going semi-Capitalist themselves. Then again, given the better standard of living and increased influence, they may not mind.
So I'm wondering whether "My Mark of Cain" by Albert Brewer was post-war, or post-humous. Seems like it would be an interesting read as an autobiography.