Yes, that makes sense; thank you for the info. My H90 setup has a Mission control H9 expression pedal on EXP 1 (which works great); and I am looking for a 3 button device that can extend the full functionality of buttons 4-5-6 out of EXP 2.
So far I have tried a TC Helicon Switch 3 that a friend loaned to me, and the 3 buttons correspond left-to-right to 4-5-6; but the buttons do not support momentary use. I also have a Pigtronix Universal 3 button box that sequentially DOES NOT match the H90 (it is wired to work with the H9, according to the company website), and DOES NOT support Momentary use.
Would it be possible to implement a feature, in the future, to assign individual buttons via the H90, so as to allow for more third-party pedals to work with the H90?