That’s very interesting, especially the mouse part. I hadn’t thought about remapping its buttons to anything related to KDE, and unfortunately I don’t think that is possible in mine.
I am also surprised you can manage 20 desktops in two monitors. How much ram do you have, both in your brain and in your computer?! And the part where the grid is synced between the screens also feels a little weird to me, but even though I only use a single monitor, I can definitely see the appeal. Obviously, the biggest issue with doing that is that you have to have corresponding workspaces on both monitors at all times, but with 20 workspaces on each side, you can certainly get a lot of combinations. You could get two instances of firefox open in a different sets of workspaces, one for work and another for leisure, for instance. Firefox profiles are great for that!
Even then, I need to say it, 20 desktops on each side is a lot. For such a large number, you could consider activities, but since you seem to change desktop through the desktop grid, with no need for shortcuts, I can see how it becomes more manageable. Your setup seems very creative and unusual, at least for me.