All applications are traceable if you do not set mftrace.application.
Use mftrace.application to restrict tracing to a specific application. If the name of the application's executable does not match executable-name, all preceding configuration entries are ignored and the remainder of the configuration file is not processed.
To restrict tracing to the myapp executable:
... mftrace.application=myapp ...
To restrict tracing to the otherapp executable being run under a trigger program:
... mftrace.application=(otherapp) ...