@BenLee The problem is actually in the crossdoc syncing a Text type column, that happens to have an email address in it. When it’s in the Crossdoc table, and I reference it via Row.eMailTextColumn, or even hover over the Row column so I can see all the values, it’s not showing me the text email. It’s showing me an @-mention of the person (they have access to the doc that contains the crossdoc table). Oddly, when I add that Column from the Row object, it is added as a Text type, but is still resolving the value to that @-mention. Of course when you hover on that you can see an attribute of that is the email address under a .Email reference. However, I can’t do Row.eMailTextColumn.Email because it doesn’t recognize it as a People. object.
There is something that is being translated, unnecessarily, when sync’d through. Or perhaps it’s just trying to be smart and if an email address is entered into a text column, it will create a “hyperlink” (mailto) for it. Is there someway to turn that off?
Update: I seem to have worked around the bug. In my main table, I created another Text column, let’s call it eMail2. I set a formula on it to be eMailTextColumn.ToText(). This column now syncs properly without any special handling. So I suspect that it has to do with the code related to making the email address a mailto link that is causing the problem in some way. Unfortunately, removing the link from one of those cells and syncing again didn’t fix the problem, but should have, in theory, been handled the same way as forcing a .ToText() call on the same value. 
PS: Is there an @-mention for Coda Support so I can avoid having to submit these things in two places? It’s probably better this issue be visible to the Community as others may run into it.