Because your dimmer controls the load to light 1, even if your code worked you’d be changing its dim state in order to control the others, plus a person will find it really fidgety, low XAF.
The point of a dashboard is that you can use it as a wall mount control panel, showing only the devices you want. So good xAF for most adults, but not necessarily good for little kids.
In your situation, I personally would leave the dimmer as is and add the SmartenIT 3 toggle to control the other 3.