The Chinese government is also a competitor to Boeing (Comac and AVIC). Seems difficult to believe China can provide truly independent oversight over certifying airplane or engine products designed by their own government.
If China was our major supplier for Aircraft with a good record for reliability, but their latest model went down twice in six months in similar circumstances, would we ground that model?
Perhaps. I don't know, but I don't think your comparison is the correct one.
https://theaircurrent.com/aviation-safety/what-is-the-boeing...
Competitor is a bit strong given that even the Chinese airlines don't want to fly the domestically designed planes.