MNT Reform Keyboard 4.0 (Standalone) firmware backup/change howto

Hello Folks

My mnt-reform v4 keyboard standalone arrived.
I noticed that there isn’t an insert key and I want to change the left ctrl for the hyper key.

And I would like to change the rgb backlight color but this isn’t top priority.

MNT Reform Standalone Keyboard Manual (V4)

This manual has only a few details about the v4 keyboard

I found the gitlab repo and clone it:

git clone https://source.mnt.re/reform/reform.git
cd reform2-keyboard4-fw
# the README.md file has only instructions to build but I don't understand how to make the changes ?

Where can I find information about which packages do I need to backup the current firmware. I’m using GNU/linux :stuck_out_tongue:
The mnt-reform v4 keyboard standalone has an option called “usb flashing mode”. is this the option for flashing in this model ?

How can I help with the documentation ? I would like to learn how to modify a few keys and help with the README.md

Thanks