Wix FAQ search seems to be operating off the site’s original language. When I switch to another language, the questions and answers are in the selected language but search does not allow me to find the translated text. If I search using the words from the original language, it does find the entry.
Another unsupported multilingual capability apparently. This applies to FAQ as well as site search. Wix Multilingual Request: Using Wix Site Search with Wix Multilingual | Help Center | Wix.com