MFC-Edit isn't officially supported on Mac OS X Catalina at this time. Apple have changed something in Catalina (I don't know what that something is at this time) so that if you upgrade your OS you may no longer be able to launch MFC-Edit from the desktop icon or from the Applications folder. You can still launch MFC-Edit and it works fine if you follow these steps:
- Open A "Terminal" session from Applications->Utilities->Terminal.
- Copy this command: /Applications/MFC-Edit.app/Contents/MacOS/mfc-edit.sh & and paste it into the Terminal window and press the RETURN key