Experimentation in game as to what command the console could read, turns out the commands:
$game_player.actor.  sensitivity_vag=/+=/-=x

$game_player.actor.  sensitivity_anal=/+=/-=x

$game_player.actor.  sensitivity_mouth=/+=/-=x

$game_player.actor.  sensitivity_breast=/+=/-=x

all work, despite not being listed anywhere as valid commands.

Still the only in game reference to sensitivity seems to be during rebirth, and its effects are not stated anywhere, with no reference to it on the wiki or anywhere.