Yes, that gap is normal. The upper panel on the rear hatch will always have more of a gap then the forward panel it meets up with. This is by design, because the rear panel needs to lift open and close whereas the forward panel should remain fixed and have a tight seal to limit water access. Basically, if the upper portion of the panels are aligned, don't worry about the lower portion gap (the width of the rear hatch panel will always be less than the forward panel, so it's impossible to align them perfectly). If you look at the photo in the first thread, the upper alignment is perfect with a more noticeable gap below. But even if it was possible to adjust to reduce the lower gap, it would just create a larger gap between the panel and the roof glass. It would also jack up the alignment/gaps on the other side of the car, since the lift gate is one piece.
In regards to the gap between the rear and forward panels, there needs to be enough clearance to prevent damage when the lift gate swivels open.