Probably the most head in the sand mil-tech article I've read in long time. There are very few explicit claims the author makes about Chinese capability that can be addressed, most of it just gesturing at anecdotes or vibes.

The author does not notice that the F-35 is a single engine jet rated for VSTOL flight characteristics. The F135 is required to produce that much thrust by itself to support that profile. The J-20 is a twin-engine fighter. Why, pray tell, does the engine designed for a twin engine, land based fighter designed for carrying large payloads of air to air munitions need to beat the thrust of the F135? The comparison is worse than stupid.

The Chinese Flanker fleet is being built out and maintained at scale with WS-10s, it's industries churn out 100-120 J-20s per year, all with twin WS-15s. This is a mature jet engine capability, at massive scale. "Not made in China"???

The author makes a passing comment that the WS-15 is "outdated" compared to NATO forces. They are clearly blissfully unaware that the F-18 Super Hornet standard runs the F414 powerplant, as old as the WS-15, itself an upgrade on the F404 powerplant, 50 years old now. The F-18F is the USN's mainline pacific theatre fighter.

I honestly believe anyone who considers the Chinese jet engine program to have been a failure to have perhaps lost some marbles along the way. It demonstrably is not, unless you think the PLAAF is about to collapse midair, a notion their daily ADIZ violations and interceptions over the SCS and the Taiwan straits should thoroughly disabuse. My prediction is by 2037 the entirety of Chinese domestic civil aviation will be running the C919 and they'll be a serious competitive threat to Airbus and Boeing.