Worksites (especially course-sites) need to support a language/locale preference that trumps the language/locale of the user and of the system. Specific application for this include language-based courses.
Set new SAKAI_SITE_PROPERTY flag: org.sakaiproject.site.LOCK_LOCALE = [locale-identifier]
The LOCK_LOCALE property could be set in the Worksite Setup tool using a checkbox. If set, the locked locale would be equal to the user's current language/locale preference.