When you specify the lengths of the template after measuring them, the values to adjust the image position are automatically calculated and applied.
In [Advanced Settings] for the custom paper you are using, select [Registration to Align Front and Back Images Using Template].
Enter the value you wrote on the printed template.
Select the item you want to enter and use the numeric keypad to enter the value. You can enter values from 0.1 to 999.9 mm in 0.1-mm increments.
Press [OK].
Press [Exit].
Press [OK].
Press [Overwrite].
Press [Yes].
Press [Exit].