None of the actors speak Mandarin that well, and the inclusion of Mandarin alongside current commonly-accepted Chinese indicators - such as the fabrics, cut of clothing, food & use of chopsticks - don’t reflect a great familiarity with the either Chinese or the diaspora…
I just want to posit this one unlikely but possible reason to why there is Chinese culture without Chinese characters. It is possible that the Chinese were completely wiped out during earths history, and then ages later the ancient culture was rediscovered and for some reason it flourished afterwards. Much like the rediscovering of ancient Greek culture during the Renaissance that was called Humanism. Maybe?
There are Chinese people - but they only show up in the background.
Plus the level of integration seems skewed for that to happen - while I could see the study of ancient Chinese as being a mark of culture and breeding, it doesn’t then follow that the use of Chinese characters literally everywhere, and the use of spoken Mandarin (at least to some level) by all ranks of society, could be based on anything but total integration.