Hauptwerk doesn't assign the Continuous Controller to work with your expression pedals (crescendo pedal also). If you check out page 41 of the HW User Guide, you will learn how to auto-detect the expression pedal that is in your console so that it controls the HW object on the screen you are auto-detecting. You have complete control over the decision. It doesn't have to be a pedal on a console. It can be a knob or slider on a MIDI keyboard. It must be a Continuous Controller though.
You can also do the setting of what Continuous Controller does the job manually. Check out page 150 in the HW User Guide. Remember: YOU get to assign the physical controls that operate Hauptwerk, not the other way around.
I hope this helps, John.