I don’t have time to analyze the whole thing right now, but high level overview, your brain compensates for uncorrected astigmatism. After a shift in astigmatism correction, changes to the visual cortex/lens/whatever stabilized after 6 months. The effect was measurable in only 2 hours, which leads me more towards the visual cortex theory, which is a lot more adaptable than the lens of the eye. The study is of course going the other way, adding lenses to someone who was previously adapted to no lenses, but the reverse seems reasonable.
What does this mean for those of us with complex lenses? Well, the fact that your progress though cylinder is slow is well documented. Try not to be frustrated or push to go as fast as you did with sphere.