Have you tried selecting a Scale feature and simply changing the root note to adjust semitone? Note that will only work tho when connected to an instance of KK and not globally in MIDI. Not sure you will ever see a semitone shift in the keyboard since for most people, shifting semitone on the keyboard is useless, you kind of expect a C note to be a C note.
Best alternative solution is simply to load a MIDI effect in your track, I would assume FL has something like that available.