Note off release problem

Hi! I am new to scripting, I know a few things (cannot stress the "few" part enough . I recently found here a fairlly simple true legato script by @Levitanus (thanks, mate!). This is the thread: https://www.native-instruments.com/forum/threads/transition-samples.182674/

So, i am trying to make a legato instrument that has the following groups: sustain, sustain after legato, release, 12 leg up & 12 leg down transitions (from minor second to octave interval each). So, I have adapted the script to my needs group wise, and so far so good.
But the problem that I get is that when a second key is pressed while the first is being held down, the first key remains pressed up until I stop playing legato and play the corresponding key on my keyboard "non legato style", effectively playing the same note again, but as a sustain. I should mention that there is no audible hanging note, only the key is graphically represented on the Kontakt keyboard as being held down. I believe this happens because of the note_off command in the "on note" callback, that by definition must happen before the key is released, in order to crossfade to the legato sample. So, as I understand, what happens is that by that time the engine is already done processing that event and does not anticipate a note off command for it anymore.
I also found this: https://www.native-instruments.com/...d-release-callback-when-releasing-key.230481/
which is, I believe, directly related to the same problem for the same script??, but although I tried implementing the different methods in the cod, i't appears to be well above my head, i really don't understand what is happening there...

Could someone please give me some advice, or push me in the right direction at least? Thanks!