One option is to open Properties menu (toolbar) and then check the report path under Box Path

You can then use that in a script
Names Default To Here(1);
dt = Open("$SAMPLE_DATA/Penicillin.jmp");
fm = dt << Fit Model(
	Freq(:Count),
	Y(:Response),
	Effects(:"ln(dose)"n),
	Personality("Generalized Regression"),
	Generalized Distribution("Binomial"),
	Run(
		Fit(
			Estimation Method(Logistic Regression),
			Validation Method(None),
			Confusion Matrix(0.5)
		)
	)
);
fm << Confusion Matrix(1);
ncb = Report(fm)["Logistic Regression","Confusion Matrix","Training",NumberColBox("Misclassification Rate")];
rate = (ncb << get)[1];
					
				
			
			
				
	-Jarmo