The Main menu is not working either.
Scripting for *.grub2 does not work because there is no regexp module loaded, so the script cannot find any files.
if exist fred.grub2 will work, but if exist *.grub2 does not work.
OK, so it is not simple to make it working ....
It is a pity, since you are so close to having UEFI Secure support for your program.
How to make Ubuntu Or Linux ISO booting with persistence support without using extraction of the ISO ? Is it possible ?