After working with my client for over a year, I have finally got higher ups in Microsoft Mac Development to acknowledge this bug and they are currently working on it. At least in our instance, the issue stems from activating too many fonts with a 3rd party
font manager like Suitcase of FontExplorerX. The amount of fonts is usually in the 3k range, which then causes Office 2016 to act all loopy and throw up random error messages.
If you aren't using a 3rd party font manager, then your issue could be different. For those that are using a 3rd party font manager, Microsoft Developers are working on this and they expect a fix in the next couple of releases. I'll keep this thread up to
date as I find out more information.