Forgive me for maybe having misunderstood it, but it was my impression that the C919 is certified to standards which are non-compliant with those of the FAA and EASA, meaning it won’t be certifiable within those jurisdictions.
Could be that the CAAC are testing the waters, wanting EASA to quantify the delta and a provide a path to compliance. If the aircraft can be made EASA compliant, then it should certifiable by the FAA as well.
If it can be certified; if COMAC get their after-market support in order; if it comes with acceptable performance and maintenance guarantees; if it’s offered at 75% the price of a Max or Neo, then it would stand a decent chance of enjoying some success outside of China.
Strategically it’s obviously a whole different ballgame, as it’s not really in Europe's interest to finance China’s ambitions for the C929, as well as the eventual C939 and C949 models. On the other hand, China is projected to account for 25% of sales of all commercial aircraft seating +100 passengers in the next 20 years, a demand their local industry has no chance at coming near meeting. It’ll be a delicate balancing act.