The Nuxeo application should have only English display only?
1) In the browser, set language preferences. Japanese on the topmost. 2) It’s okay if login screen shows Japanese but, after login, the Nuxeo application should have only English.
Every user can choose its language preference in his home, user settings.
You can try to force English at login page using that URL:
http://localhost:8080/nuxeo/login.jsp?language=en but the value will be overwritten by the user preference.
Finally, if you want to forbid any other language than English, you can create a bundle which will erase all other translations and be loaded after the bundle named
org.nuxeo.ecm.platform.lang.ext: in that case, when no translation corresponding to the browser language or user preference is found, then the server language is used.
By default, Nuxeo maintains English and French translations. We also got a lot of translations for other languages, including Japanese. You are very welcome to review and contribute an update if it's out of date.