If I understand correctly - "?locale=he" from url is copied into AppContext.locale interface when the app is loaded and not changed afterwards. If url does not contain "?locale=" then AppContext.locale is not defined, and when EXB opens, it will set the locale to a fixed default value of "en".
What I still do not know is how to cause AppContext.locale to be "he", even without adding "?locale=he" to the url.
In orther words - does React enables it, to "force" AppContext.locale to be "he" as if the user had entered "?locale=he"