Discourse currently has Traditional Chinese (zh_TW) and Simplified Chinese (zh_CN) localization. However when I have the browser’s accept-language set to
zh-HK first, Discourse errorneously selects
zh_CN as the default language.
Most users from Taiwan (
zh-TW), Hong Kong (
zh-HK) and Macau (
zh-MO) prefer Traditional Chinese, so for these accept-language values Discourse should select
zh_TW as the default language instead. (Technically you can also make use of Unicode CLDR likely subtags information, but for just Chinese it would be a bit overkill.)
I also want to point out that, having “中文” and “中文 (TW)” in the language selection is extremely weird. It really should list “简体中文” for Simplified Chinese and “正體中文” for Traditional Chinese instead.