Alas, I can't actually go back there right at this minute, but at least I can still keep tinkering with the photos. Still using Hugin, but using the PTStitcher engine rather than nona and enblend. This allows for colour and brightness correction, and has a different way of blending the borders. I also leaned how to add extra contol points to control horizontal and vertical features, which has left me with a much better horizon. At least I'd like to think so. There are 2 ways to make these things better. One is to use a tripod and the other is to learn how to use the camera better to lock down all the brightness/exposure settings. Even if I only locked the camera settings, it would already have made it much better.
Edit: While I'm on a roll, here's the Nourlangie Rock and Arnhem land photo redone similarly.