The key points to understand here are that each entry has a 'root ' specification which tells grub where to find the files that are described. EVERY FILE AFTER THAT is RELATIVE to the 'root' of that file-system.
In my example it literally looks for the '5th' partition on disk zero (sda5), then looks for the file boot/... within that file-system. Since the file-system in question is normally mounted on /boot after mounting that file must be found in /boot/boot/... That's what the symlink to . named boot accomplished in my prior email. It effectively turns boot/ within that file-system in to a no-op; thus making things easier for normal users, as long as they don't need to set things up again like you are.