I’m not entirely sure where the right place to put this is. It’s a file format issue in part, since if people can’t keep using Finale after a macOS upgrade, they need to salvage all the files they’re created in its proprietary format.
The email which I got from MakeMusic, dated October 18, was alarming:
Finale v25.5 is not compatible with macOS 10.15 Catalina and will not be updated to support Catalina. It is our recommendation that users of Finale v25.5 not upgrade to macOS Catalina.