I don’t think there is any way China can revamp her image in Asia due to the fact that so much negativity and tension is instigated by the US. Japan and Korea are US allies “vassals” and so their media and politics are usually on the side of the US. In this situation, anything China does, no matter how benign, will be twisted in an negative light. And the only way it is not put in a negative light is when China gives way, in which case other countries can just continue pushing and pushing. It’s like someone who bullies you, and when you don’t fight back, it’s ok, but when you defend yourself, the bully cries foul. You can’t win in the bully’s POV.
The SCS issue has been longer standing for decades. Even Taiwan does not give up on the 9 dash line. If I understand correctly, Taiwan still uses the 11 dash line, which held more territory. China has tried in the past to jointly develop those oil fields with other asean counties but there was never agreement. I don’t think China has these policies for the sake of been aggressive. If it was not important, they would have let it go a long time ago, instead of letting this issue cause headaches.
As for xinjiang, these policies to reduce terrorism are necessary especially since lots of isis fighters are from xinjiang and can cause havoc. Maybe it’s a bit too heavy handed but overall there need to be More stability and increased jobs for those in xinjiang. There are no easy solutions but education is key. Development of the Silk Road can offer job opportunities. I think they are trying to use the policies to try to clamp down on unrest, and their mentality maybe that they rather over do it, then try to increase economic activity and improve jobs and livelihoods in xinjiang to make it stable. Rather then under suppress that region.
There’s a lot of things that happen behind the scenes that I probably don’t know about but I did realize that it is very difficult to improve your image as a country when someone who controls international media and has had much more experience with the global media empire is constantly biased against such country. Eg. In the past every time China had an issue with the island dispute with Japan and sailed a ship close to the island waters, China was he aggressor and it’s always chinas fault, never Japan’s. In actuality, when China and Russia were doing a joint military excercise, Japan would fly recon planes into the middle of the exercise, disrupting the exercises. Not a peep about Japan’s aggression. Another example is to look at the bbc, when China had he virus in feb, Wilbur Ross gloated that industries will come back to the US, bbc didn’t complain and somewhat supported his views. Now when the US had the highest rate of virus and protests and China only pointed out he irony of their previous gloating, the bbc ran an article on how China is gloating and pushing their advantage. They twist anything China does into something that’s malicious. When a senator said China is sabotaging the US ability to make a vaccine and China won’t share a vaccine, there was no evidence presented, but the bbc always mentions how China pushed conspiracy theories about US military bring in the virus. They didn’t even mention that trump tried to buy sanofi vaccine for use only in the US. In my mind, No point in trying to please their media, just continue with what makes China stronger.