Switch / Button / Double Button / Dimmer / Eltako

So I don’t understand why 3x2.5 is installed. 1.5 would be completely sufficient and you wouldn’t break your fingers wiring it. But that doesn’t matter for the problem.
So every lighting circuit goes up to the distribution board you say. Then at the switch there is only one cable coming from the box? Or two, if it is a double switch.

I don’t want to write anything wrong here and this is a gray area. In principle it would be possible. If it were my house, I would just do it that way. The problem is that the blue conductor may only be switched in exceptional cases and a mix-up must be excluded. Basically your 3x cable runs into the distribution where various blue wires are connected together. Only this one from your switch is not. So a mix-up is not excluded.

I can draw that for you... it looks a bit dumb but it shows you how it would work.

My training was unfortunately a few years ago and nowadays I work more in industry than in house building. Therefore my drawing is unfortunately not so great, but it should still work.

On the left goes the 3x2.5 to your switches, which cannot be replaced anymore.
So the blue has to be switched. In the distribution the blue is connected with the brown via a terminal. So the “signal” is basically forwarded through the distribution to the relay.
At the relay the 5x is connected accordingly and the “output” from the relay can continue to operate the spots with 3x2.5.

Oh, before I forget. Don’t rely too much on the color. It can also be that in your switches brown, blue, green-yellow run. Then the brown is with permanent power and the black is switched to the relay.

So I don't understand why the 3x2.5 is installed. 1.5 would be completely sufficient and you wouldn't break your fingers when wiring. But that doesn't matter for the problem. So you say every lighting circuit goes all the way to the distribution board. Then at the switch there is only one cable coming from the box? Or two, if it is a double switch.

I don't know why either. Maybe he wants to break his fingers. Every lighting circuit goes all the way to the distribution board, correct. And just as you say, one cable comes from the box and with a double switch of course two. Great, thanks to you! I will present the whole thing to my electrician, after all, he knew that we mostly want push-button switches. Then he has to implement it accordingly.