If you deployed Office 2016 with a volume license, chances are your user will complain that the name used for reviews (or Auto-Track changes) is "Microsoft Office User" with initials "MO" (or any localized variation).

It is stored here : ~/Library/Group Containers/UBF8T346G9.Office/MeContact.plist

I started an idea, but don't have the time to figure out the Initials: