That is a valuable bit of info on swinging the ph, I never would have thought the plants would tolerate such a swing. I've had drift happen on my first few grows from 6.1 to 7.6. I am phasing out dolomite lime and replaced it with ph neutral gypsum and Epsom. I am going to try and swing the existing soil for next round with your method but the opposite direction.
It works the other way around too. I have a similar issue that I've been slowly fixing. My pH also wants to rise. I figured out it was because all the Ca amendments I was adding, plus my 7.2-7.5 well water already has a little Ca. I've cut a lot of that out, and have been feeding with more acidic water.
I'm not trying to do it super quick though since I'm doing a living soil, and I'm not sure how some of the critters would appreciate a super acidic solution. So I've been using liquid organic nutes or epsom salt to help bring it back down slowly. I haven't gotten the soil pen I need to really know for sure, but I get an idea testing the runoff, just not a great one, lol.
My best advice would be to listen to
@DoubleAtotheRON or
@Renfro. These guys know some shit, lol.