The long and the short of their complaint seems to be that the treaties are unfair. Well excuse me. Isn't that what happens when you get your butts kicked? The Brits kicked your butts and you had to give us Hong Kong. You could have not have signed it, but then we might have kicked your butt some more and asked for a bigger bit. Isn't that how treaties work?
It's what the Americans did to Mexico, and they ended up taking a third of the damn country, so isn't the message quit bitching? You had a choice when you signed the treaty guys. You could not have signed it, but everything you do has consequences. At the time it probably didn't look as damn irritating as it looks now, you were just grateful to stop us (or the Japanese or French or whoever) kicking your butting.
You don't hear us complain about the Eastern Seaboard of the US do you. After the War of independence we signed a treaty recognising them. We don't go to them now saying "We still recognise you but can we have the East Coast back?" do we? You don't heat Mexico saying they'd like California and Texas back do you? The Chinese should do the same, suck it up and stop whining. They're a world power, but that doesn't mean they should act like bullies.