Regarding a "mandatory duty" here I really don't agree with You. I don't think neither China's security nor integrity will be affected if an aviation enthusiast finds out like the question about a certain fighter's engine.
Hmmm
... since in real live I'm a teacher for Chemistry I still believe more in the scientific research by close observation and logic to come to an conclusion. That does not mean I'm always correct, but usually it is a better way than listening to rumors and again I have my observations that tell me it is an AL-31FN while so far everything in regard to a WS-10 is plain rumor; honestly NONE of them is near close to a Gram of "counter arguments"; sorry.
At least - and that's indeed a pity
since I can't understand Chinese (like in this video) - I would like to ask You to tell me what's these arguments !! Please. So far I only heard that this and that source is quite reliable, but no-one showed or explained me these counter-arguments even more in direct comparison to the other arguments. As such please do me that favor and explain.
Anyway if You think so and if You feel to have better sources then You might be correct and in the end time will tell.
Again ... I don't think so. If You simply compare all images we have, both engines are exactly the same at least externally. So maybe simply another AL-31FN-version.
I sadly can't understand what they say but even in CCTV several of these reporters do not know much more than an average forums-reader. IMO mostly they get their information from the same sources like we. Even more if there's a special guest like a "legendary pilot" they also do not tell the truth every time since they are not allowed to do. As such I would take this as an deliberately spread rumor to lead away from the facts.
Additionally that J-20 CG-model shown alone in the first seconds is even less reliable ... so not much more credibility for a "new engine" IMO.
But again only my opinion.
Deino