This is tough, because I would like to see China as more sensible than Russia, and their help to Russia does not seem overwhelming.
Still this is cause to worry IMO. Because China claims to support international law, but training troops to fight in an illegal war against Ukraine is obviously contrary to supporting international law, as China claim they do.
I still hope China will be a more reasonable player on the international scene than what USA has become, and will adopt a more EU like approach of prosperity through cooperation.
If they do we will have a bright future ahead on both sides. If they don't, the world will become a lot worse than during the Pax America era that is coming to an end. Because China could become even more powerful than USA used to be.

Both China and USA have trainers active in the Ukraine right now, and they always have and always will.

Don't take it personally, war is a very lucrative business and China and USA are both very active in almost every conflict around the world (either directly or through proxy).

It's just business.