With my account set to the US region, my English language search returned simplified Chinese characters in the Quick Answer results.
Query:
ethernet switch? site:news.ycombinator.com?
Results:

The bullet with Chinese cites the following two pages, but neither contain any Chinese: 6, 9
For thoroughness, I will note that my default Kagi Assistant custom instructions contain details of my Chinese language learning and relationships. I would not expect that to result in Quick Answer inserting, seemingly at random, Chinese characters in an English-only query, despite them being grammatically and semantically correct.
I expected a Quick Answer that used only English.