This is incredible. Why can't the PLA just come out and say that the Y-20 is now flying with WS-20 engines. Or that the WS-20 is still in the testing phase. What is the big deal about this ? Why can't people know about this ? There is no reason for this secrecy.
Tthere was an article about it in the Global Times.
The PLA seldom does "official" press releases or emit public statements.
At best it will show up in next military parade.