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, enter the value using the number keys, and then press [].
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].