The docs don't mention that you cannot do this. They only mention what it does when you enable the "uninstall" feature.

So by default, the Uninstall feature will "reverse" whatever in the installation action set.

However, not all programs behave this way (for example, if the install action set is: launch executable setup.exe). So the uninstall just runs the same executable, which of course, doesn't uninstall (MSI are different as they're usually configured with an uninstall switch).

So, I was wondering:

Can I still enable Uninstall, but customize the Uninstall Actions within the Action Set?

So I could put in (or change) the Launch Executable setup.exe to like:
launch executable msiexec.exe /something or whatever the program uses (maybe it's a setup.exe /remove or something--I don't know)