Like I said it helps because Russia has more technical expertise with civilian aircraft manufacturing than China does. They would be able to supply any know-how or components which China does not have yet. It is all about risk reduction. And, like I said, the Russian market itself is not insignificant. Aeroflot alone operates close to 100 A320/1 aircraft and almost 40 737s. The MC-21 was never meant to replace 100% of these aircraft. It was supposed to replace half of them at best, and half of the MC-21 were meant to have Western engines. The market for large aircraft is way smaller, Aeroflot operates over 40 A350/330 or 777s total.
If China manages to make a version of C919 without Western components Russia would likely buy it. Because like I said the MC-21 production line is not dimensioned to replace all their Western aircraft of same type. They plan to expand it but it will require massive investment. Russia at one point, when Medvedev was in power, wanted to have a production facility for Xian MA60 in Russia but it was decided not to go ahead with the project. Back then it had limited technical advantage over older An-26 aircraft still in service. But the major issue was the Western engines made it not cost competitive.
Outdated technology doesn't make sense
We have a lot of engineers, including retired Boeing and Airbus and Antonov, so Russia is pointless
C929 never thought of cooperating with the Russians
It's just Putin's proposal and it turns into politics
Not only will CR929 fail, heavy helicopters will not cooperate with Russia
A lot of inside stories are not as optimistic as you think
95% chance of failure of China-Russia cooperation
You see Chinese propaganda will never show the foreign engineers we hire
But the fact that we do employ a lot of foreign engineers
Agreed that cooperation with Russia is meaningless, no technology, no money, no market
and extremely arrogant
The composite material used in Russia is Zhongfu Condor
But Russia boasted that it was made by itself
The natural gas ship built by the Russian Eastern Shipyard is made in South Korea and used by Russia to boast that it is made in Russia
Some Russian radar originals are imported into China, but Russia also boasts of domestic production
You seriously exaggerate Russian technology, look at Russia in the Ukrainian battlefield hahaha