The Russian jet engine designers have very good aerodynamic knowledge that is applied to their fan, compressor and turbine airfoil parts. What is significantly lacking is the capability to manufacture the parts to the design requirements. When the Soviet government owned and ran the jet engine businesses, everything was a paper transaction. The more engines produced, the better, full employment forever. What the parts cost, let alone total engines was a mystery. Maybe that is changing now, but it will take awhile.
Meanwhile, the story in China is different. They have very acceptable manufacturing knowhow and capabilities.What they have been lacking is good design knowhow and design experience. They are gaining that knowhow rapidly by one means or another. IMHO, they will be a major jet engine player quickly.