I found this thread when looking for help on getting the wonderful Scroll Reverser running on Catalina. The author has a note on the website saying that Catalina is causing issues and there is not yet a fix available. For me, the app would launch and immediately segfault. The icon for the app would appear for a split second on the menu bar and then disappear.
I experimented a bit and found a workaround which works for me and might work well for others too.
It involves using the automator tool on MacOS to create an "application" which launches Scroll Reverser. Just one action required which is "Run Applescript". Below is the body of the action.
do shell script ¬
"'/Applications/Scroll Reverser.app/Contents/MacOS/Scroll Reverser' \\
>/dev/null 2>&1 &"
So create this automator application, save it into your applications folder with a new name eg.
Scroll Reverser Catalina and run it.
On first launch, it will require the user to allow for security & private exceptions in the areas of "accessibility" and "input monitoring". After ticking the boxes for
Scroll Reverser Catalina in those security & privacy areas, it runs as expected.