I can't tell you that the roof TPO membrane ripples are "normal" or "not normal". Pictures may help. Some "ripples" will be visible where the OSB sheeting joins, some may be visible on a hot day. But you shouldn't have "deformity". In other words, some may be OK, but without knowing or seeing what you're seeing, it's difficult to say, "it's OK" or "you need to take this to the dealer for inspection".... Photos ????
As for the rear wall, the FILON sheeting on the rear wall is "free hanging" and is only attached at the top, bottom, sides and where windows, vents, lights or other fixtures are installed. So, you will see and feel a "floating" rear FILON panel. It will move in and out as you push on it. That's perfectly normal.
Oh, welcome to the forum, we're glad that you're here.
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS