Google Calendar failing to sync on a specific account
I actually fixed my problem by deleting and re-creating my user account. I chose to keep the home folder in place and used it as an existing folder when I created the replacement account.

While I was troubleshooting everything I was monitoring the logs and saw no error specific error messages. The only thing that looked suspicious was a message about CalendarAgent returning status 4. I wasn't able to find a reference for that status message.

If I understand it correctly, the problem would had to have been in the /var/db/ directory in order to get fixed by an account deletion.