Maybe someone can refer me to a study that mentions this. But one thing I have noticed is that the handful of videos I've or descriptions I've read of people going out looking for ball pythons in their habitat, happened during the day. It makes sense, to; that's when we can what were doing, plus it's easier find then by racing into a hole you know they occupy than by hunting the brush in the dark.
But we all know that ball pythons are nocturnal, or at least, most active at dawn and dusk, and secretive. In generally, we often know a lot less about the habits of nocturnal animals because it's harder to observe them without disturbing their behavior.
If most of the firsthand accounts are from the middle of day when we all know they're likely to be asleep, why should we assume that means they never venture anywhere at night, just because it's harder for us diurnal humans to watch?
One last comment.... all this discussion of climbing is about climbing all the way to the top of an enclosure 12-24" high. That is hardly a stratospheric height. Plenty of ground dwelling animals climb up things that are knee high - we're not talking about the top of a giant Sequoia here. I don't know why it should be so controversial that a mostly terrestrial animal might like climbing things that you could step over, whether you call it terrestrial or semi-arboreal or whatever.