recently i have same issues as well
as far as i know,the publishers of these spams are mostly from Bangladesh rather than China. They use machine translation to pretend to be Chinese and mostly point to a website:
www.latestdatabase.com
and this is their ip:
103.155.118.53
i think you can ban these ip and add a filter instead of ban chinese character
for example,you can usecomposer require fof/filter:"*"and add "www.latestdatabase.com" to filter,it's more useful
（using google translate because i am not good at English）
