It's all about what can be considered practical ad-judgement of just how close to "perfect" something needs to be.
In your case, when bounce flashing off a surface when using a reference level Flash, the raw umber in SS would have to react, albeit very slightly. Enough to really matter? Only you can judge.
For all extent and purposes, when "projecting" onto SS, the extremely small amount of adjustment via calibration required to get to neutral makes SS among the best of choices. Of course that flew in the faces of those who condemned SS on the basis of it not being absolutely perfect. That....and the fact that "as is" it delivers a sub unity gain surface. SS is what it is, that's all that it is, and all it purports to be. Which BTW happens to be more than adaquate for many people,.
That Auto Table is pretty cool. Thanks for introducing it.