Russia’s Zarya module was constructed not by Russia but by the late soviet union before it dissolved as an additional module for the Mir space station. Russia’s contribution was to repurpose inherited hardware for use in the ISS. Given the very spotty track record of Russian space endeavor with anything that was even partially developed after the dissolution of the USSR, I would not suppose Russia to be capable of developing a reliable follow on the Zarya today.
Also, keep in mind the only real collaborative joint space effort between china and russia up to today, the Fobos-Grunt mars mission, failed spectacularly because multiple elementary failures of Russian upper stage. Having many elementary systems fail does not lend confidence to Russian ability to make anything complex work with a reasonable number of tries.
The russian inability to get simple things it has done many times before working during actually mission contrasts sharply with the meticulous Chinese approach, which test the hell out of everything and then succeeds in acoompolishing multiple envelope pushing features simultaneously on the first try in space
One might say this culture difference is likely to make any serious collaborative effort between Rosocosmos and CNSA a marriage made in hell.