I doubt there are Russian companies assisting Chinese AESA development. Maybe Russian experts and engineers just like how there are Chinese experts and engineers in American defense industries, along with any other nationality e.g. with a Chinese engineer in ATF project back in the 90s.
Russian companies have not been able to field an AESA on their ships yet, let alone their fighters. Su-57 is still a work in progress as admitted even by Russian official commentary in that they wish to hold off orders until the new engine is completely ready. Certainly that is not the only factor delaying their 5th gen fighter. The other factors they don't want to mention and the keen spectators don't want to admit to themselves.
All the available indicators point to Chinese radar industry being far more mature and capable than Russia's today. Perhaps Russians have some better stuff or leapfrog technologies but when it comes to AESA, it is hard to believe Russian companies are of any assistance. Which Russian companies are involved? If they are happy to tell public figures that they are assisting Chinese AESA development and also disclose the state of their client's abilities, shouldn't these companies be well known? Phazotron or Tikhomirov have never officially stated such things and they WOULD have stated and advertised this every single minute if it were true particularly if they are happy to tell "insiders" such sensitive information about their clients.
This kind of BS propaganda is so weak and easy to see through yet so many believe it. Explains why the US is concerned with Russia's behaviour and continued efforts to wage psychological warfare on the west even though the RF no longer poses anywhere near the military or economic threat the Soviet Union once did.
This AESA business is about as believable as saying Chinese motor company is now assisting Mercedes Benz with developing their latest internal combustion engine They need to try harder with the BS in future