Full text search does not search for some translations. (ex. en_US, ko, ja)

I use Xwiki's multilingual features to translate technical documentation.

When a document in English is translated into Korean, if the keyword is searched, the original page en is searched, but the translated page is not searched.

As a result of my testing, it seems that English, German, French, and Spanish specified documents are properly searched, but Korean are not searched.

If the locale is "en" or "default" and you put Korean into the page, it will be searched well.

Also, it seemed that the translation page that specified locale was not retrieved even if it was in English.
(en -> retrieved, en_US -> not retrieved)

I changed the Sandbox page to Korean and searched the "Edit" keyword, but the Korean page was not searched.