Actuate.stop(target, null, true) should apply the final values of the animation (as if it had finished normally). In case of a reverse'ed tween, these should be the original values of the target, but currently the values provided to Actuate.tween are set (the starting values of the animation).
target.x = 10;
Actuate.tween(target, 1, { x: 20 }).reverse();
Actuate.stop(target, null, true);
trace(target.x);
// outputs 20, should be 10