Can I add more custom cutouts from my original background image?

If when starting your design, you opted to add some custom cutouts and leave some off, but decide later to add it back in, you can use the Create new option in the Custom cutouts panel.

Opening the custom cutouts panel will show you all the cutouts you already created. If you select the Create new tab there, it will show all the objects we detected that you opted not to cutout. Click the objects you want to add and then click convert to cutout.