The correct command is M106 P2 H2 Tnn where nn is the temperature at which you want the fan to turn on. You can also add an S parameter to limit the fan speed, although for thermostatic fans the firmware enforces a minimum S0.5.
Looks like you've used the wrong sign on your H parameters. The H value at a point should be (trigger height at that point) - (trigger height at centre).
Note, using H-corrections may sort out the calibration, but you will not be able to use mesh bed compensation, because that doesn't know about trigger height variation. But well-built deltas don't normally need mesh bed compensation anyway, provided that the bed is flat.