I think detecting the centre of a pad made out of printed ink, or fiducial out of etched copper on the board would be relatively simple to probe for automatically, likewise user drilled vias.
I propose for edge finding of a positive feature to get the user to roughly align the probe with the centre, then:
* Probe the point for a height reference
* Move sufficiently to the side, based on the gerber data to hit bare board, and then get a height reference for the board.
* The probe is advertised as 20um accurate, so either raise up 20um and move inwards towards the pad until the probe activates - or move the probe till it touches the pad and then move in all directions until it "falls off" the pad.
* Find centroid of the pad from the touch or fall off data.
I prefer moving from outside in, as pads can have significant variation in height where the "kiss" is in the centre or when it has been printed over multiple times. The edge seems to be more reliable for height.
Likewise, this could be applied to vias, where you would touch off the board, and then drive towards the via until you "fall in", raise the probe and then move to the other sides and drive inwards. Determine centroid from this data.
This would give much more precise positioning of features on the board - be it fiducials or vias for ink deposition, or pads for paste deposition (especially when you have very small pads getting pasted!)
Even if you are pasting a pre-fabricated board with full ground pour/adjacent tracks, I feel the probe tip is fine enough that you would be able to detect the gap between copper layers even with 0.2mm isolation, assuming 32uM copper. I haven't measured the tip diameter to determine this though.