Thanks for the offer, Jack. I actually got the FCB UNO2 working with Live earlier today. I ended up modifying a setup file that another user had shared by making just a few important changes.
I changed each Effect which had NoteOn and NoteOff commands written in them to CtrlChange commands. I found out that control change, rather than midi note on/off messages, allows me to use midi learn to assign each pedal to the on/off button of an effect plugin in live so that when I step on a pedal, its red led lights up, and the corresponding plugin turns on... just like my analog pedal board. I ended up programming 19 FCB pedals as UNO 2 "Effects" to control on/off buttons of plugins in Ableton LIve and 1 other pedal as an UNO 2 "Trigger" to control Live's tap tempo button.
One other change I made to the FDB UNO 2 setup file was to simply change the midi channel from 1 to 15. For some reason, when the FCB was set to channel 1, Live would receive midi messages from the FCB and allow me to assign controls via midi map, but (mysteriously), after I mapped any of the UCB's foot pedals, upon testing them, none would work. At that point, I noticed that my Arturia keyboard controller was transmitting on midi channel 15 and all of its mapped controls worked well, so I thought I would try changing the midi channel, and surprise: it worked.
Anyway, I think I'm in good shape now to continue learning about the UNO 2's features/capabilities and applying that to more interesting ways to control Live. It's going to be fun. I'll post my current basic setup file here in case it might help the next newcomer!