Measure my 1st runnings, subtract from pre boil volume, and sparge with a volume that should be about 1/2 of pre boil volume. (temp about 190, after it is in MT it is about 167). Vorlauf, collect.
With a high pH you'll risk producing significant tannins with a 190-degree sparge, even if the mash grain bed drops it down a bit. So, I agree with the others that this was primarily a pH issue.
In keeping with the spirit of batch-sparging, my process is very simple. For a 5-gallon batch, mash in with about 4 gallons of appropriately heated water to hit the target (I'm flexible with grain/water ratios but with a "typical" 11-lb grain bill the mash is about 1.5 qt/lb). Drain the tun, check the volume and add the necessary sparge water heated top about 170-degrees to hit the preboil volume (it's usually also close to 4 gallons unless it was for a bigger beer). Stir well, rest ten-minutes and drain (I mash in an 8-gallon kettle with a simple bazooka filter). I'm usually looking for about 6.5 gallons pre-boil.
So, I don't do a low-volume, higher-temp mash-out between these steps as you do and I feel things have worked well enough. I don't see any reason to be concerned about the grain/water ratio for the sparge if that is what you were also concerned about. That step is about getting sugars off the grain - the mash is done.
Everyone has their own way to make great beer - so find one you like and have fun!