Using TMC driver for as emergency stop - lost steps

Lost steps mean that the stepper was unable to rotate further.
I’m really not sure that in the case of homing Z, there is a case and that you would be able to detect it because of the high torque from the lead screws.

So, unless your nozzle is able to stop them, there is a high chance it would go unnoticed.

FWIW, you could test that you can detect on your motors:

I did fast test, well

Pressure on the table, unnoticed.
Hand braking the rotor is noticeable.

Hope that helps.