CONF1 comes from FCOM1 1.22.40 at P6 there are the activation conditions and one of them is to have CONF1.
In my opinion, but i may be wrong as i said before, between 2300ft and 1500ft you have NO alerts on the ND but you should have only the aural synthetic alert voice from the PWS system as "windshear ahead". This is what i get after reading and comparing FCTM and FCOM1.
