Individual aftertouch to volume on a held chord

Aftertouch equally affects all the currently playing notes. Keyboards with Aftertouch were only able to take the maximum pressure applied to all/any of the aftertouch sensors under the keys and use that to affect all the notes being played.

Polypressure, or poly-aftertouch, was a later addition where the pressure of each key could be measured and transmitted separately. This meant that each note could be modulated individually.

Most instruments in Kontakt will respond to polypressure so, from your description, that is the one you should be using.

The [touchin] and [touchout] objects only deal with aftertouch values so they are not what you are looking for. There are no corresponding objects just for handling simple polypressure inputs and outputs.

So, you will need to get used to using the [midiformat] -> [midiout] object pair to output your polypressure data. You feed the note number and pressure value (as a two integer list) into the second input of [midiformat].