Awesome, glad you sorted it out. I think the "back panel" is usually the middle of the first page, at least for a typical trifold layout, maybe there are others.
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I guess so. Whilst I studied illustration at university, we were taught that there is the Exterior panles and Interior panels, which are read 1-3 left to right when looking at them, so the side of the paper that features the cover would be exterior, and so forth, with each panel being numbered E1, E2, E3 and so on. Guess it is different around the world.