I am currently using Docker to run vtigercrm/vtigercrm-8.3.0. However, I noticed that there is no option for Chinese in the Language settings under Personal Preferences.
I found in this document (https://help.vtiger.com/article/147105221-Vtiger-Language-Support) that Vtiger does support Chinese.
I tried installing the language-pack-zh-hans within the container, but it did not resolve the iss