What is Firmware.scap in the /EFI partition?
I suspect the second file is a security update. The 1st one most certainly is a no-fly zone.
Has to do with firmware I think.

However, never ever mess with your (U)EFI partition, or you may have a very expensive Apple doorstop on your hands...

Well, my own EFI partition is mounted here. You can mess around with it all you like on an external bootable USB stick.

I'm doing this just to see if I'm able to run an unallowed version of OSX on a very old, already scrapped Mac Mini.

OS bootloader seems to depend on (U)EFI, namely...
Revive a broken bootloader/ EFI partition, and you may do wonders. I think.

Just look at this:
http://xpcboot.weebly.com

Have fun, but don't break a working Mac...