If people thought that chinese exchanges were selling them non-existent coins, the way to quickly find out if its true or not is for people to pull their BTC off of the exchanges and see if all the sudden they run into "technical difficulties" and stop withdrawls.
Why they reluctant to withdraw ? because the situation is some of them provide
interest of storing bitcoins by lending and borrowing (or some similar financial product )on their platform . This strategy really works on many greedy guys .
AND , many Chinese players are new to crypto they don't know how to withdraw bitcoins to onchain-wallet ( blockchain.info ,qt .etc) ,onchain-wallets are too difficult for them . So , they put their bitcoins on trading platform . I know it sounds ridiculous but it's true .
Even if they offer interest, you withdraw the coins, then within a few minutes, deposit back. Those few minutes that the coins are off the exchange is meaningless in terms of lost interest, however it does prove that they have the coins. Of course, everyone would have to do it relatively the same time for this to actulally work.
Can't read Chinese either, and google translate sucks. So how did you come to the conclusion that they're trading with coins they don't have?