I hate to say it, but this sort of basic grammar mistake ("KEEP CLEAN AND SMOOTHNESS" instead of "KEEP CLEAN AND SMOOTH") really bothers me. For such an important project meant to establish China as a trustworthy commercial aircraft supplier on the world stage, perception is extremely important. For this incredibly obvious, incredibly noticeable typo to exist, with it being in red capital letters underneath the captain's window, a mistake that any native speaker or ABC would have caught immediately, is hugely disappointing.
A third party that sees this will inevitably wonder what other mistakes were made, which gives racists and State Department operatives an avoidable opening to generate fear, uncertainty, and doubt about the aircraft.
COMAC, and China generally, should internalize that perception truly matters on the international stage. Polish and presentation can be just as critical as engineering prowess. Gaffes like this really add up.