I still clearly remember my mate who works for Toyota telling me, after he did some work on my previous TRD ronron, that you want to drive it hard after a tranny reset to get the base learning more peppy.
I'll admit, I didn't really ask any further about whether that becomes the low-level default or if over time it changes to whatever your driving style is like, but I know that when I set myself a challenge of going absolutely grandpa for a week or so to test fuel conservation, I didn't get any annoying shifting traits.
I really hope you manage to get to the bottom of it, because I know I'd be crawling up the wall if I was getting that sort of flare 😞