Your play-back engine has to map each note to something (a drum sound).
Obviously, Toontrack is smart enough to re-map known notes that do not exist in a simpler kit to some obvious alternative - they are, after all, their kits.

If you get some wild MIDI file that uses notes outside what your particular sound engine maps, they simple will not play.

As I recall, you use Studio One. If you play with Impact (even a little), you should be able to get a good feel for how it all works

https://www.youtube.com/watch?v=_XqXPnP3e-Y