If I may talk about the broad geopolitics of this war for a moment...
First of all the war isn't really between Russia and Ukraine, it's between NATO and Russia. That's a big part of the reason why Ukraine has held up so well. It's not just because their "oh so plucky fighters" are so great. It's because the West has provided massive moral, intelligence, material and manpower support to Ukraine, not just since February 24, but for the last eight years. If you look at NATO with its massive population of 950 million and huge economy of US + EU, and compare it to Russia, it's clear that Russia with its 145 million people is actually the underdog in this fight. Sure NATO troops aren't directly involved, but the support they are providing is making a decisive difference in keeping Ukraine alive.
In my view, for NATO, they don't really care about Ukraine, they see it as an opportunity to bleed Russia and ultimately destroy Russia as an independent great power. It's all about Russia.
Which leads us to... IMO if you're China, Russia cannot fall no matter what. If Russia returned to the complete abjection of the 1990's and Yeltsin-style politics, it could be forced to host Western bases on its territory. In other words, China could potentially face Western bases not only in places like Japan, Guam, and South Korea, but in Vladivostok and Irkutsk, and even in places like Kazakhstan. That's the dream of the Western strategists. In such a case, China would be completely encircles in all directions with a hostile India.
Supporting Russia will be painful for China, unfortunately it has no choice if it doesn't want to be entirely encircled. Therefore China's going to have to take significant pain and risk further Western sanctions in order to provide aid for Russia. IMO even if that means transferring lethal weapons to Russia.