Hi, I have just found description that seems to be mistake.
on https://marketplace.zoom.us/docs/sdk/native-sdks/web/advanced/multi-language
Change Language when a User Joins:
//Add the language code to the ZoomMtg.reRender method.
-- ZoomMtg.reRender({"jp-JP": lang});
++ ZoomMtg.reRender({"lang": "jp-JP"});