I think the biggest problem is, there are simply none or at best to few information available "to prove" what you asked for. As such - at least to my understanding - in the public there are no official data given on specifications and so on.
In essence, a clear absence of a "proof"!
However there is plenty of information available on different scientific achievements relevant for engine technology and - at least for me - we have numbers of aircraft in service which speak for themselves:
We have now almost 250+ J-20 in active service, most likely close to 300 built. Since mid-2019 none of them (new-built ones) uses a Russian engine anymore and even if again we have no "hard data" on performance and more so on reliability, maintenance, time between overhaul and so on, the fact that the PLAAF seems to be satisfied stands against how many operational Su-57 with AL-41F engines?
And if you go one step further ... the WS-15 is in test, allegedly even in LRIP ... and where is the izd.20 aka AL-51F? Actually based on what I know it is built in smaller numbers, used in only one prototype and everything else is "announcements and we plan to ..." for the future.
Hope this helps a bit.