Dan’s tested the Goldsmiths Disklavier. All keys are working, as are the damper and una corda pedals. He suggests limiting your MIDI velocities to 100 as anything higher is phenomenally loud and liable to disturb the tuning or perhaps even damage the instrument. See the post below for how to handle velocities within the midi-play method.
the middle (sostenuto) pedal does not seem to be responding to controller number 66.
the Mark III manual does confirm that the middle pedal should react to controller 66 :/
MIDI Velocity 90 is LOUD on the dislklav. Go up to 100 at your peril!