Thanks Lilibet for such warm welcome! From my understanding, Jenny comes from a very normal family in a second-tier city in China. Her parents probably aren't well educated. However, this does not mean they see themselves too weak to seek justice. TONS of average Chinese families with loved ones that are victimized and unfairly treated by laws are blasting their stories on social media seeking justice nowadays. I'm not sure if you are following Yingying Zhang's case, but her parents never gave up and flew all the way to America to look for their daughter. That is a normal reaction when anyone's daughter has gone missing. So initially I did find it very bizarre that Jenny's parents are so easily satisfied just because the Chinese Embassy told them someone saw her still in Mexico, and that was months ago. I would have expected them to cry out for help all over the place by now demanding assistance to find their daughter. But no, they are hushed for obvious reason which you have mentioned, "not push the Mexican government in order to maintain friendly trade relations". ALSO, we should keep in mind that their daughter Jenny is very much hated on social media. Her weibo posts have portrayed herself as someone who disliked living in China and longed for a better life in USA. This obviously did not sit well with the netizens in China, and after her weibo account went public, there were so many horrible hate messages written on there saying things like "nobody would regret it if she actually died in Mexico". So, let's assume her parents were not bought off or threatened by anybody to keep quiet, they probably still wouldn't scream too loud about finding their daughter. Not only would they not get what they want, they are probably risking their safety by doing so. Just to give you an idea about how power the netizens in China are - there was once a case of animal abuse and the woman's social media account was exposed with horrific pictures of those poor animals, people on the internet were able to find out her real name, home address, work address, phone number, ID # (similar to social security #). And then some of them got together, cornered her on her way home, and almost beat her to death. This is the sort of things that Jenny's parents would be facing if they "seek justice" for their daughter, maybe not this extreme, but still.
With that said, given what I read from Jenny's weibo account, I don't think she was delusional or had mental problem. She was a naive and extremely adventurous person (not a good combo). And if she is voluntarily going missing, her first choice is definitely not to return home to China. She simply is moving on to another adventure.