Hi!

Great job for now ; just a little mistake in the setmessage. You can use “+” operator to concatenate, but it will only work when the script is computed (at loading). To perform it in real time, you may use the {} (braces with javascript inside) :
run("setmessage current 1, midi://midi_out/notef 1 {cursor_id/127}");

Be aware that you’re using /notef in floating format (‘f’ => needs values between 0. and 1.). You can also use the /note that uses integers (between 0 and 127). So it could look like:
run("setmessage current 1, midi://midi_out/note 1 cursor_id");

Hope it is clear!