To see the results from Photo Mechanic's variables, you can add these variables to the Set Info Text dialog, from the Settings option in the Edit menu.
Click the Variables button to open the list of Variables. The Camera section at the top of the Variables list will have Exif variables. Just double click a variable in the list to paste it in at the current cursor position in the dialog.
This variable info will be displayed in the Preview window's Info panel. Use the Show Info Tool Tips option from the View menu, to see the same variable info on the contact sheet.
Best regards,
--Bob