EFIUpdaterApp.efi checks if version is 1,1 or 1,0 Changes what i make was 2 or 3 checks of CRC checksum not one.
Also i did not download update from site.I push autoupdate in control panel apple firmware is download then he ask me to reboot i cancel it then copy from apple update files firmware update tool and remove firmware checks.But my firmware version was 1.0.
So the only think that is left is to be removed current firmware version check.This can be done by hex editing EFIUpdaterApp.efi and searching for string that check what is your current version.
And this string must be changed to firmware 1,1 string so result will be maching and EFIUpdaterApp.efi will flash libreboot I alredy flashed my macbook1,1 (works very well ~ 1-2m after flashing) and can`t test this.
