MacOS keyboard layout not working on linux trough barrier(synergy)

my issue is rather complicated, so I do not expect to find a solution, but maybe someone has had the same issue before me.

My workspace is composed of 2 computers, a mac and a Pc running linux Manjaro.
To avoid having 2 keyboards, I use the one of my mac, with layout CH-DE.
I'm having some trouble using Barrier(Synergy) between the mac as server and a linux as client.

My issue is: when typing alt+Shift+7 to write "\" this does not work on my client machine where instead I get: /.

On both machines I have set the keyboard layout to macintosh CH-DE and every combination without alt+Shift works correctly.
The key combination altgr+Shift+7 works perfectly fine if i'm using an external wired keyboard keeping the keyboard layout to macintosh CH-DE.

I had to struggle with Barrier even to reach this situation. I had to use a config file on my mac that looks like this:

section: screens
    MBP:
        halfDuplexCapsLock = false
        halfDuplexNumLock = false
        halfDuplexScrollLock = false
        xtestIsXineramaUnaware = false
        preserveFocus = false
        switchCorners = none 
        switchCornerSize = 0
    manjaro:
        alt = altgr
        halfDuplexCapsLock = false
        halfDuplexNumLock = false
        halfDuplexScrollLock = false
        xtestIsXineramaUnaware = false
        preserveFocus = false
        switchCorners = none 
        switchCornerSize = 0
end

section: options
    relativeMouseMoves = true
    screenSaverSync = true
    win32KeepForeground = false
    clipboardSharing = true
    switchCorners = none +top-left +top-right +bottom-left +bottom-right 
    switchCornerSize = 0
    keystroke(<) = keystroke(<,*)
    keystroke(Shift+>) = keystroke(Shift+>,*)
end

Note that I had to map the alt key to altgr to make it work.
Also the < didn't work properly: adding keystroke(<) = keystroke(<,*) solved the issue.

So, I tried to add the following possibilities to solve the alt+Shift+7 problem:

keystroke(Alt+Shift+/) = keystroke(Alt+Shift+/,*)
keystroke(Alt+Shift+/) = keystroke(AltGr+Shift+/,*)
keystroke(Alt+Shift+7) = keystroke(Alt+Shift+7,*)
keystroke(Alt+Shift+7) = keystroke(AltGr+Shift+7,*)

But none of those options worked.

My question is if there is an (other) way to solve that issue?

Thank you in advance for reading my question and your reply.

By chance I found the solution for XFCE working for any keyboard layout.

Open Settings > Window Manager and go to Keyboard
select a empty case and click edit. A window should popup with Press any key
Press the key combination that isn't working on your host machine. In my case it wrote out Alt+Shift+/.
Press the clear button and click again on edit.
This time use the wired keyboard on your client machine and press the exact same key combination. In my case it wrote Shift+Backslash. (AHA! That's also the difference ...)
Finally, edit your config file by adding the keystroke modification under Section:. I my case I had to add: keystroke(Alt+Shift+/) = keystroke(Shift+Backslash,*).