clonezilla the backup / restore utility
should best be booted from SD card. Then you can easily edit the /EFI/boot/grub.cfg, setting the language to your country, like fr = France, de = Germany asf.
replacing the kernel parameters in the same spot can preempt the regular bash scripts. You could just replace
with "sh" and explore
/usr/sbin/ocr* - the various bash scripts which clonezilla offers
/lib/live/mount/medium - your SD card where you can save stuff to, if you booted clonezilla in "toram" mode
To produce a custom clonezilla booting into your custom-bash-script, you may want to unsquash clonezilla's main squash-fs, modify it, and replace the original on SD. Just rename the old one but keep it on SD, so you can fall back to default Squash-fs at any time with no effort (just rename the 2 files from your main Linux on the FAT32-formatted SD card).
Clonezilla has a sequential text menu, but it tells you the shell commands needed to quickly call any repetitive task such as backing up the same source drive to the same target on a routine basis. No big deal to call such a shell script from
once you escaped to shell.