FWIW, one of Word's product team, without seeing this thread, has written that "The list should be populated when Office first contacts the Research service; when that
happens, the right set of dictionaries are populated based on the set of languages you have enabled.... If there’s nothing there [that is, in the Research Options dialog], it’s likely we failed to contact the service. In terms of troubleshooting, it would
be useful to know what happens when those users hit the 'Update/Remove' button and try to update the 'Microsoft Office Online Services' group." My understanding of this is that you should proceed in Add/Remove Programs as you would to "repair" Office and do
something with the check box for "Microsoft Office Online Services." Perhaps set it to "Do not install" (or whatever the wording is), finish the "repair," then go back and set it to "Run All from My Computer" again to kickstart it.