Hi Charlie!
Well, we thought about this case but it’s not so easy (what about polyphony, when there are multiple y positions for a given x-position?).
But you can have a look at the example “Xenakis Metastaseis linear” that is very close to your question (thanks to the messages arguments collision_curve_id, collision_xPos, collision_yPos, collision_value_x and collision_value_y, cf documentation).
Hope it can help you!