Well, I hope one of the really knowledgeable desktop-computing people on this forum will help.  Yr. humble servant is basically a system administrator who has rather little to do with the X Windows System in any form, most days.

I do have a MacBook Air running Debian 9 'Stretch' in a virtual machine.  In that environment, right-Command-key clicking emulates right-click, which is a darned good thing because right-clicking is essential for the Window Maker environment.  You might be amused that I gravitate toward Window Maker because, in bygone days, I was a huge fan of NeXT, Inc.'s NeXTStep, a proprietary BSD Unix whose current offspring is Mac OSX.  Window Maker is an X11 window manager/desktop that's deliberately in the style of NeXTStep.

The Debian installation does NOT have an /etc/X11/Xorg.conf file, and instead relies (I guess) on Xorg hardware autoprobing and defaults.  I've not looked more deeply because it Just Works[tm], so I haven't poked around much.

Give that a try, anyway.  'Hope it helps.