I only used freebsd-update once and never seen any error like you posted. I googled for some of those errors, but you seem to be the only victim of these errors.
You could post your issue on the freebsd-questions or freebsd-stable mailing list. That way Colin Percival, the programmer of freebsd-update will learn about the issue.
Or just bite the bullet and backup your system, install the latest and greatest and restore/merge configuration files from backup.
There are some guides here about dump/restore and disk cloning.