Deliveries have stopped.
Two things are happening. Indigenous avionics and custom built EW systems are being trialed and fine tuned.
Second, Russian engines are being trialed as well.
Russian engine on J15? So does that mean that the Chinese engine is still not up to par? I thought WS10 had gone through enough iterations and testing that it was now at the level where China was shifting away from importing Russian engines to power its jets...Obviously you want a tailor made system, and not an identical one in service elsewhere.
...and started using WS10 variants on its flankers, J20, and J10.
WS10 engines on J15 would also have commonality with WS10 engine on J10. So it seems very puzzling to me