I'm sorry but even as being an author of this PPA I do not have a solution.
Downgrading Xorg and patching it may end with difficult long deep dependency resolution.
I tried to install Xenial HWE packages from my PPA on Bionic with no luck.
So there is something wrong inside Unity or GNOME sHell.
You can read my complete opinion on Ubuntu Community (first and second). I cite latter here:
The universal remediation to fix current bug - do not use both GNOME sHell and beloved Unity
and purge them with commands below:
sudo apt-get purge gnome-shell ubuntu-gnome-desktop \
ubuntu-desktop ubuntu-unity-desktop unity-session
sudo apt-get autoremove
but use Cinnamon, KDE, MATE (my favorite) or Xfce instead with packages from my PPA:
#Choose your favorite desktop
#sudo apt-get install cinnamon-desktop
#sudo apt-get install kubuntu-desktop
sudo apt-get install ubuntu-mate-desktop^
#sudo apt-get instal xubuntu-desktop
#Add my PPA
sudo add-apt-repository ppa:nrbrtx/xorg-hotkeys
sudo apt-get update
sudo apt-get dist-upgrade
#Reboot and enjoy
Optionally pin (lock/hold) related packages to prevent their upgrade with:
cat <<EOF | sudo tee /etc/apt/preferences.d/pin-xorg-hotkeys
Pin: release o=LP-PPA-nrbrtx-xorg-hotkeys
If you are not satisfied with obtained results - write a letter to Mark Shuttleworth / Xorg / GNOME / all bug-trackers / all IRCs / all LoCos / all treads of Ubuntu-Forums / Bill Gates about your problem and then execute:
sudo apt-get install ppa-purge
sudo ppa-purge ppa:nrbrtx/xorg-hotkeys
sudo rm /etc/apt/preferences.d/pin-xorg-hotkeys
If you would like to complete with installation of MATE DE you can use Mutiny panel layout to avoid some headache :)
The last option - you can try to write PM to the user, suggested to downgrade Xorg to give you complete working instruction.