If I understand correctly, the midi CC messages are all coming through on the same OSC address, with the knob number and the value both as return values. I don’t think there’s a way to address just one of the knobs directly, but you could use another live_loop to split out just the knob(s) that you want into separate keys (obviously adjusting the OSC address for midi CC messages and the knob numbers to match what your nanoKontrol2 sends):
live_loop :midicc do
use_real_time
knob, value = sync "/midi/nanokontrol2/something/control_change"
if knob == 1
set :knob1, value
elsif knob == 2
set :knob2, value
end
end
live_loop :midi_piano do
synth :piano, note: :e3, amp: get(:knob1) / 127.0
sleep 1
end