Is being shy and quiet a respected character trait in China?

Yes, it can be viewed as a respected character trait.

In Chinese, shy and quiet is viewed as 斯文 [sīwen], which also means polite, soft-spoken, and refined, and is a good character trait for both man and woman (especially woman).

Why would a shy person be respected for just being shy? But If I'm not mistaken, I learn that in some Chinese cultures in China, they may be considered a good trait, especially when for a girl who reaches her suitable age of getting married/forming a family. For them, being shy and quiet are considered a courtesy. But in modern city in China, I don't think being shy is very relevant anymore.

there's not preassure on them to be calm, that's just the way they're raised. there's some pretty crazy people in china who are loud and party animals, but a respectable family raises their kids to keep composure at all times. they belive that if they get too riled up or excited about something that that'll put a bad chi and junix it and their luck will turn sour.

probably or it could be that you came from a different state or different skin colour and im chinese but i dont believe that.

Quiet yes, everybody hate noisy people here, but as for shyness, well, some people like extroverts, some people like introverts, we're no difference from other people in the world

Being shy and quiet equate to being refined. An example of an educated person who measures his time and situation to speak or voice out. It may not be respectable nevertheless it is being cultured and culture is make through history and cultivation. The American culture could be just opposite.
Modern China is slowly changing its culture and we see more ABC (American Born Chinese) or trained having westernised trait everywhere.