What exactly can anyone in the Vatican do about this?
There is nothing that the Vatican can do, because it too has been infiltrated.
Essentially the situation in China has brought us back to WWII, or the French Revolution, or the liberation of Poland. Take your choice; it's bigger than all three of them.
Secondly, it's time to realize that the solution will require martyrdom; it always has.
And lastly, the situation is going to need both an experienced leader/leaders who are already positioned, and some international teamwork and cooperation.
This trial with Trump is just a minor distraction designed by the opposition (it always has been) to draw attention away from the real problem.
The grand design which always failed before, is for Communism, (political) Atheists (Religious), and Socialism (Humanism)...aka the Unholy Trinity... to finally overtake the world, and work through the hands of The United Nations.
So yes, it's big.