>

Or a very spiteful  person.
The ones that signed are sponsored scholarship students that probably represent more than a couple of million dollars worth of investment.
China is more afraid of someone finishing their training, running away and claim asylum. A young trained doctor will easily find shelter in any first world country. >

China has police stations in foreign countries to deal with this. If you are of Chinese descent, you are not safe from the Chinese police in most major western cities >

Anyone else find it weird that we call these police stations? Obviously in western democratic countries these police have no way to effect a legal arrest or detain someone. Unless they step into an embassy. They have no way to legally compel someone to step into a plane and return to China, they operate using blackmail and other underhanded tactics. Supposedly they convince 220,000 people in a year to return in this way. Supposedly 2 passenger planes of people a day are compelled to return to face crimes in China.
Why are so many Chinese people committing so many crimes against the state? How are the Chinese police so effective? Didn't you hear, it's impossible to escape the Chinese police. 
...Are these claims part of the fear tactic? >

They may not be able to legally compel someone, but they can make the lives of any family still living in mainland China a living hell.  It's not about physically coercing them onto the plane.  It's about insinuating all the terrible things that will happen to mom and dad if they don't do as they're told. >

I don't doubt their blackmail capabilities.
So there's over a hundred Chinese police overseas stations. If we believe the numbers, each station is coercing 6 Chinese people a day. Shouldn't we have something like safe escort services for when Chinese people visit these stations to renew their passport so they don't get blackmailed in person? Require proceedings to be done in English with a real domestic officer present? >

That's the thing about blackmail, though.  It's illegal, but if the people report it, what is the US going to do about what China is doing to their families in response.  Let's assume that these people report the blackmail to the authorities.  The Chinese government then finds some reason to raid their parents' home back in China, convict them of some trumped up charges, and their families suffer political pressure until the person decides to cave in and go back home to mainland China.  No country has a right to interfere with another countries legal system, so China is essentially holding everyone hostage.  The proceedings could all be done in English in front of a domestic officer and it would go along the lines of this:
"Have you heard from your family recently?  I hear that the Chinese government is cracking down on social activists.  Say, didn't your mom make a post criticizing the government not too long ago?  Seemed pretty critical to me, anyway.  You should probably go back home to China and make sure that she's doing well.  It's good to take care of your mother, after all."
And there's nothing that any country would be able to do about it. >

We need good anonymous reporting and tracking of these issues so they can be logged. 
The only solution I see for these people is to completely cut ties with your family and make yourself uncontactable so that blackmail on your family can't be used. I know that's not realistic for 99% of people, especially students or those who are on a temporary visa. >

China doesn't care whether or not you've cut ties with your family.  They will hurt them until you come back because it costs them literally nothing to do so.  They can throw them in a political prison where they will never see the light of day again and forget they ever existed and it wouldn't cause the Chinese government to blink at the effort.  Combine this with the heavy enforcement since youth of the importance of family bonds and taking care of your parents and you've got yourself proper leverage.
Not returning to China when urged?  We'll throw your parents into prison for speaking out against the government.  Don't care about your parents?  That's fine, neither do we.  We'll keep your parents in prison and wrangle up your cousins, uncles, and aunts and do the same.  Don't care about them, either?  Then we'll start hunting down your old friends and colleagues from before you left and add them into the mix.  Seems like a lot of people that you've known while growing up have suddenly started talking bad about the Chinese government.  How much are you willing to bear the responsibility for?  How much will others suffer until you cave to the demands?  How many of your loved ones will be in a cold and moldy prison cell begging for you to come home and cursing your name every day that you've abandoned them? >

So basically, this systems great weakness is if they try and use it on either a sociopath or a true believer.