[morzh]

A hysteresis motor with 4 poles (2 pairs) will have at 50Hz the speed (synchronous) of 25 rev/sec or 1500 rpm.

You have 4 poles, so it will be that.

>>four windings and two starting windings are switched on through the phase shift capacitor.

Where do you see 6 windings? I see 4 altogether.

As for "not even three, but four windings", with synchronous hyst motors the windings in stator come in pairs. The speed will be your AC frequency divided by the number of pair (with 4 windings you divide by two, hence 25 rps or 1500 rpm).

True synch motor does not need speed regulator as it cannot possibly exceed the synch speed, it can only achieve it and lock to it.
The centrifugal regulator in asynch motors is not the speed regulator but the "start capacitor switch". It does not regulat speed.
If you do have starting cap and the centrifugal switch, then maybe it is not a hysteresis motor after all?

The synch motor simply does not need anythingm, winding or capacitor, to start, as it develops torque right from the get-go, amd the torque does not change with the speed as it catches up with the field rotation.