I worked for a subsidiary of the Hainan group and it was a great gig. BCA. All HNA crew could jumpseat on other HNA carriers so I talked to a lot of other crews at other HNA carriers, including Hainan.
Hainan Air is probably tied with Jun Yao as the worst carrier in China for expats. I would bet in their own view, they don't try to treat expats bad, they just treat them like they treat local pilots. The problem is, the way they treat each other, is horrific.
I just went through a different agency to try to go back to my old airline. They tried to talk me into Hainan, and said their was a change in their attitudes towards foreigners, for the better. Unfortunately, that might just mean a change in attitude by one person in their office that recruits foreign pilots. More than likely nothing else has changed.
There is a chance that there is a change for the better, but I wouldn't bet my career on it. I would recommend going with a chinese carrier that has a better rep for dealing with expats. ALL chinese are the same in some ways, which unfortunately is the medical, which all pilots do at CAAC (FAA) hospitals and medical staff. There is no way around it currently.
Hainan Air just raised all their pay rates, lowered their recruiting requirements, in the hope of getting more applicants.
They are currently offering NTR positions on the 787 and 777, with very low required Boeing time in other models. If you go for this deal, you are a test pilot for your career, with a carrier that has a reputation for 1+ year line training (for type rated pilots). As an NTR applicant on a wide body, you will be a JR captain after your 1+ year of line training. God knows how long this will last, as no one has done it yet successfully.
BCA, Spring, Shenzhen, Tianjin, Sichuan, Chengdu, Air China, China Slowly, Xiamen, OK, and SF all have had reasonable amounts of success recruiting and hiring foreign pilots. Going with the one that has a horrific rep, based on the promises of some 23 year old in the recruiting department, is probably a recipe for disaster. I would recommend letting someone else be the test pilot on this one.
Hopefully the ones that apply will have better luck than i just predicted. But i wouldn't bet my own career, or money, on it.
Good luck with your choices.