You're right in the fact that the controller you're looking at is a series of on/off switches, but it's how they are programmed is where the issue is. There's nothing wrong with your terminology. The problem is with the understanding of sales and support of this product. Honestly, I'd have preferred them to say, "I don't know." It would have been more honest. Or even "The Stage Setter 8 can work with any MIDI controller capable of sending note on/off signals, provided the MIDI controller is able to send the correct signals".
There are so many controllers out there, that coming from a lighting making company, it's really not their responsibility to track this sort of stuff or at least directly research it. They also don't want to say "hey, these MIDI controllers work" because they could get tied up into some sort of "we endorse this product" sort of mis-understanding that can get users up in arms, or various competing makers angry at Elation or ADJ.
It takes someone who doesn't work for either company to say "Hey, this works or this doesn't work, at least in my experience". Even if on their "official support forums", this is OK because it comes from a third party that is NOT a hardware vendor.
For example, it's been PROVEN for a fact that with the American DJ, the Korg nanoKEY, nanoKONTROL and nanoPAD work with MyDMX. I can say "Fact" because I've done it. An Elation employee has stated that a certain Behringer control surface works with MyDMX. Another user has stated a specific Behringer footcontroller has also worked with MyDMX as well.
The pedal you are looking at is more of a "legacy" controller: the programming is very restricted. While it is an on/off switch, the switches are hard-programmed to send patch/program changes only. They have to use on/off switches or else they can't get it to work. But the trigger is "when this pedal is pressed, go ON and send patch change XXX", and the off is not necessary to be tracked.
In the case of a hand-based controller, such as the Korg nanoKONTROL, the controller is TOO soft in my opinion. Everything on that little controller can be manipulated. But again, this is a hand controller and would NOT be suitable as a foot controller.
There are so many things with MIDI that can be done, thanks to the various instructions and CC controllers. It's impossible for everything to support everything, except for sequencers, which ideally should support the entire MIDI protocol, which is why they tend to cost at least $100 for a decent new in the box sequencing package. For everyone else, it's a matter of reading the MIDI specs of both and seeing if they line up.
You're going to have a bit of an issue finding a controller that's going to work very well with your Scene Setter 8 for live performance the way you want to do things. It may be a good time to step up to say a DMX Operator or DMX Operator 192. These are more scene based, but you can trigger scenes by MIDI Note ON(offs are ignored). You still need a controller that can handle MIDI note sendings, and are limited to 128 of the 240 total scenes available, but that would probably be your better bet. Another option might be the ADJ product MyDMX, or a entry level Compu Live product. Still, you need a note-on capable controller for triggering.
Really, in your case, the foot controller is going to be a major hurdle with the Scene Setter as I am not personally aware of any foot pedal boards that support latching. This isn't to say there isn't one, just that's not my area of expertise.