回複：MUST HAVE the divorce judgment sent to USCIS, you can try

Any mediation agreement in China, is not the final divorce paper. Generally the final notarized divorce cerficiate will tell you that the couple is granted divorce after the mediation fails. I don't think the mediation paper is legally equivalent to the final divorce judgment. (or Divorce Certificate in Chinese).
Chinese Consulate will authenticate documents issued to US. but I am not sure whether their authentication for a Chinese version document is valid for immigration purpoes.
If I were you, I may have to get the final divorce certificate in case USCIS asks for it. You can send the mediation agreement to China and get it notarized. USICS may omit it and treat it as the final divorce judgement.