Comac C919 began commercial service 28 May 2023 per https://en.wikipedia.org/wiki/Comac_C919
If Comac C939 begins commercial service it should be reported by credible sources and appear in https://en.wikipedia.org/wiki/Comac_C939 or similar. Will resolve positively for a given time period if the program is renamed, and commercial service of plane under new name (noted in Wikipedia or similar) begins in that time period
If a similarly specified (eg approaching 400 seats, 7000nmi range, or better) new (not merely a C929 stretch) airliner goes into commercial service from Comac or a renamed/related/successor company, question will resolve to true for year range the plane goes into commercial service. If a plane named C939 goes into commercial service but is not similarly specified, question will not resolve to true.
Also see similar question for C929, a smaller widebody
1,000