Nice experiment. I've enjoyed reading this thread.
As a Brit, with relatively high alkalinity (my area typically ~120ppm CACO3, 65 Ca, only 6 ppm Mg, 48 SO4, 28 Cl, so not as high as yours), I'm used to having to add a fair amount of acid. Like Charles though, I use CRS/AMS, which I think is much more common over here; I notice that Northernbrewer don't even list it. It means being tied to a certain proportion of sulphate/chloride gain (sulphate biased), but as long as I balance that with the salts, I've had very good results in many styles. In fairness, I did used bottled water in a lager. I know some brewers use sulphuric and hydrochloric acids separately as well, to gain extra control, but I'm happy with CRS.
I've noticed lactic from acidulated malt at fairly low levels in wheat beers, so have steered clear of lactic acid. I've never used phosphoric, though I've read that can actually precipitate some Ca out of solution (?). I'd be interested in hearing your results from a different starting point, using CRS/AMS if you can get it, in balance with the salts, and seeing what effect that had on the same beer.