Never mind and apologies for the bug-report. The person who performed the installation failed to RTFM, so the changes required to /includes/classes/order.php to make a distinction between a guest order (pointing to the orders_status page) and a regular order (pointing to the account_history_info page) were not performed. That's one of the downsides of having "hidden" updates (i.e. readme-only) since a lot of people don't bother to read the readme, assuming that copying/merging the files in the plugin's distribution is sufficient.

I'm off to (1) upgrade to v1.15.3 and (2) perform the missing core-file updates.