If you know History, you know that before 1917, there was the Russian Empire, and if you know after the Soviet Union collalpsed, Russia inherited all the ICBMs and nuclear forces and all the major industry.
With exception of Antonov and Lotarev engines, most of the major industry is located in Russia.
Now by simple Euclidean math in Euclidean geometry, the shortest distance between two points is a straight line you know tha an S duct can not be the lightest solution.
Now you claim Russia did not innovate?
true? not true, at all, 117 is lighter than Al-31 and smaller and lighter than Al-41F, with electronic control systems.
Basicly is a new design, what about airframe? LEVCONs are a unique solution developed in Russia, not the Soviet Union, You thesis is basicly a nationalistic thesis that China catch up with Russia.
In our days, all nations and all industries are globalized.
The fact J-20 and J-31 look to much like F-22 means simply that knowledge passed by legal and illegal ways, the americans are claiming the F-35 technology went to China illegally in airframe as the Russian claim Al-31 went to China in the same ways.
Now that is a strategy to catch up, regardless of the fact DSIs are an american invention or faceting was first tested on F-22 and F-117, to the Chinese is not important as long as they can design by their own a stealth fighter with their own engines.
Russia is no exception, Russia also copies, and also is making trade and industrial links with France and Italy for Superjet 100 or PAKFA with India, as it is re-linking its industry with Antonov of Ukraine.
Not even the US is capable to stop globalizing its industry, Boeing aircraft is build by many nations, in fact now Boeing is as American as Airbus is French.
China is like any other nation, needs trade partners and commercial and technological exchanges.
What is pure chinese on the J-31 must be skin deep, but basicly by just pure looks the jets benefited a lot from american and Russian tech, you like it or not.
