What do you mean by "being on the level"? If the C919, C929, and C939 pull of sufficient sales, then it's clear that COMAC is one of the three companies (COMAC, Airbus, Boeing) that is able to manufacture and sell jumbo jets.
Companies don't release sales prospects based on fiction.
Technological level. Also by the timeframe stated, COMAC should also be producing the full range of jets from the smallest to the largest.