Hi @Jake, thanks for your continuous replies, it's really appreciated.
Once I boot on clover from the usb, I've got 3 choices : boot MacOs Install from OSX (hard drive), Boot MacOS From OSX, and Boot OS X Install from Install macOS High Sierra The third one works, as I am able to go to the GUI with diskutils Install High Sierra (select hard drive and such)
As soon as this process is done, If i try to got to boot MacOs Install from OSX (hard drive), I get the panic error from USB
if I select Boot MacOS From OSX, I get in to Yosemite no problem.
I'm thinking : do I need to boot in Yosemite, Copy the new files to the HDD EFI's partition and then proceed to boot MacOs Install from OSX.
Thanks so much for your time!