[Paimon]

I have found a function to give witch acceleration, this makes witch could get velocity perfectly!!

// ZombieBotLocomotion::SetAcceleration(Vector const&)
// Offsets: 97 - Windows; 98 - Linux
// For velocity z, witch must not on ground, so you need tp first.
void SetWitchAcceleration(int entity, const float acceleration[3])
{
    Address locomotion = GetLocomotion(entity);
    if(locomotion == Address_Null) return;

    float vector[3];
    AddVectors(NULL_VECTOR, acceleration, vector);
    ScaleVector(vector, 100.0); // by times 100, acceleration seems to be velocity
    SDKCall(g_hSetAcceleration, locomotion, vector);
}

Thanks to @BHaType's GetLocomotion()