I consider this more of a Suggestion rather than a request.
Semantics aside, as of macOS Catalina, the path to the default 'Applications' & 'Utilities' folders for the System Apps (Reminders, Calendar, Calculator, etc.) has been changed from "/Applications/" to "/System/Applications/". So, I think it would be much less confusing to users, especially when it comes to downloaded presets, if BTT could automatically reassign the path to a system app.
Having BTT detect the version of macOS currently in use for the system apps seems best. Another possibility that i can think of is, upon launching a 'missing' app, prompt the user to point it to a new location for the app. Or perhaps both?
The prompt would also be good for externally stored apps in which the external Volume's name was changed or some similar issue.
I don't know much about programing, so I don't know the feasibility (or system resource usage) of the first/automated option, but the second/prompt option seems to me like it should be reasonable and with little system impact.