I'm on the newbie side of things, so I'm curious to the possible reasons for this situation, because my pool dynamics are far different. Mine creeps up ph wise but TA has never moved up on me unless I added baking soda to manually move it back up. Acid temporarily drops my ph, yet permanently drops my TA. The way it always went for for me until recently was that, keeping my TA 70-90, I'd have to add acid about four days per week, and every two weeks or so I'd have to add baking soda to raise my TA. TA would always fall to around 50 over this two week period just as the calculator shows it will. I'd continue this same cycle all the time until Chem Geek gave me the solution. On this last cycle, I lowered PH down to 7.5-7.6 each time it crept up out of range as usual. but this time, I just kept adjusting down until it quit creeping back up, and didn't worry about the TA. Now my TA is around 40, but my PH stays in range, and it's CG approved.
But this post interest me, because through my own experience, I wouldn't have thought that TA could move back up after acid doses. In my experience, TA moves down with acid and stays down, while ph may or may not come back up.
But plaster makes things a little different, so I'd like to learn more.