If there is enough evidence that is beyond reasonable doubt that this company didn't hold it's part of the bargain then the pendulum swings against them, then there is proof of ownership or transaction happening.. if users can produce this then the Chinese government should give those coins to its rightful owner's because that's how a functional society sorts things out, unless the Chinese government have something else lined up.
If you are a Chinese, living in China mainland, I am sure that you can not sue the Chinese government for your benefit. Doing this is like a suicide attempt from you, so understanding this painful fact, you will know what to do for safety of yourself and your family. Finance is important for our life quality but if our physical safety has high potential of damage if we take legal action against the Chinese government, we must forget that legal action and get rid of it from our possible-things to do.
With the fact of how the Chinese government governs the nation in many decades, and how that nation is structured, you can not expect the Chinese government CCP will act for benefits of Chinese citizens.