In each case, we worked with their banking institution prior to writing an offer so we would be aware of the time it would take to wire in the funds. In all cases, their banks wired the money fairly quickly---within a few days, at the most.
If there is a delay in the wire transfer, there could be multiple reasons for that. But my experience has been that if the money is available, it can be easily wired.
I just met with Chinese buyers yesterday, and part of our meeting was discussing how they were going to transfer cash to the US in order to purchase a home.
The problem is......China limits how much money can be transferred out of the country in a year - there is a limit.......... and $800,000 way exceeds it!
In my opinion, their money should already be here, in place, before signing a contract, or be in a country that would allow such a large transfer in a relatively short period of time.
In the meantime, you are losing valuable time marketing the property to other potential buyers who could have closed escrow by now. When you accepted the offer, did you ask for proof of funds? From a US bank?
Review your contract for terms and conditions. If the time has past for certain things to happen, did you issue a Notice to Buyer to Perform? If the buyer doesn't within the time period you specified, then you have the right to issue a cancellation of escrow, and move on.
Maybe you could market your home for backup offers while you are waiting? If your current buyer comes through....great. If you get a backup offer then you can give the current buyer the choice to close the deal within a reasonable amount of time or you can move forward with your new offer.
"As you known, the foreign currency is controlled by the government in China, We are not entitled to exchange our Chinese RMB into US dollars to pay for the house.( only US dollar $50,000 per year per person allowed nowadays)......................"
Cash purchases do happen, of course, but they need to be creative in how they arrange the details.