There have been some recent analysis and banter on velocity mapping and correction of the Kawai VPC1, CA78, etc. on the PianoTeq & PianoWorld forums that are worth documenting here.
For example, "ribol" traced MIDI variability to differing heights of the rubber sensor strips on his CA78. "Ribol" acquired a bunch of rubber strips which he cut, then mix-and-matched to reduce MIDI variability. He also noticed velocity issues from the sliptape and the glue.
There are some software and hardware solutions proposed by groovy and cauldron in that same modartt thread.