I guess I know what the problem is: I assume these installers/uninstallers apps run apps in administrator mode? If so, then the RPA software must also run in administrator mode!
Reason: Normal user level apps can not control admin-level apps. This is by design. It is a Windows security feature.
Solution: Run RPA software as administrator <= it shows how to enter text into a Windows console running as admin. The same solution will work with XClicks on an installer.