the withdrawal of international partners is a very real threat. Looking at what happened to Hua wei, no international partner dared to resist the U S ban.WS-20 is not designed to civilian standard. There is a huge gap in reliability, availability, maintainability and serviceability of WS-20 vs CJ-1000A. The requirement for fuel burn rate is a lot higher for CJ-1000A than WS-20.
Let's put it this way. If WS-20 equipped C919 is available 90% of time vs a Leap-1C equipped C919 being available 99.5% of time, then no airline would be picking WS-20 engine unless as a favor to the government.
Airlines have really low margin. A 5 to 10% difference in fuel burn and having to keep around 4 times the number of spare aircraft to operate a schedule reliably will bankrupt an airline.
Again, I would really caution putting a military engine on C919 when it will put undesirable attention on the C919 program. You don't want Western suppliers of C919 to drop out when C919 has yet to be certified anywhere.