In line 42 you set the stroke to Color.NONE. So the createStrokeWidthAnimatorin line 44 has no effect anymore and the unhighlight is not animated. Set the the color for the stroke after the widthAnimator and in the else-case.

Code:
 @Override  public void unHighlight(Sprite sprite) {
    if (sprite instanceof RectangleSprite) {
      RectangleSprite bar = (RectangleSprite) sprite;
      bar.setStroke(Color.NONE);
      if (((Chart<?>)sprite.getComponent()).isAnimated()) {
        DrawFx.createStrokeWidthAnimator(bar, 0).run(250);
        DrawFx.createOpacityAnimator(bar, 1).run(250);
      } else {
        bar.setStrokeWidth(0);
        bar.setOpacity(1);
        bar.redraw();
      }
    }
  }