So this WS-20 I do see (at least for a decade) will only be used by C219 that used domestically or (if export) with customers that have difficulty on getting Western engines).
However I do suspect they have not reach parity with Western engine yet, even with the latest Russian ones. Perhaps they already reach parity with Ukrainian ones. Ukrainian engine seems with all Political and Financial problem they got, stuck with tech of the 80's or early 90's. Just speculate on that as C919 performance (even official ones), not in par yet with 737 Max or A320 Neo or even MC-21. At most C919 closing parity of 737 NG and A320 ceo which still used 90's based version of CFM56. This I look on matter of range (thus related to fuel consumption).
So I do suspect they already achieved what Russian, perhaps even West metallurgical capabilities on Turbines in the 90's. Again this's just based on the claim performance of C919 that will be using WS-20.