I understand, and I was never quite certain how the 738 gets cert as CAT C, you would have to take the MLW down pretty far for that to happen. (flaps 30 used to be the standard for cert)
Of course the speed is variable per conditions, but there is the CAT speed to consider for the procedure.
In regards to the coding, the ac is managing the speeds. While not such an issue in a straight in, but when there are turns, the ac has to use all of the variables, especially speed and max bank angle. Exceed the limits, like you stated, if it cannot get down to 140kts for the turn, you off track and disco.
This is what happened with Alaska at Palm Springs, a CAT C procedure designed for the 737-700, but when they got the 738, they could not make that last turn to final, and the ac would disco. Could not make that work with the 800.