Two Voltages Combined in a Distribution Board

I can't really read the image but if the 230vac is single phase, then I don't see a problem. However, I personally would not trust myself with the code interpretation and would defer to someone else in this forum who is more qualified.

That said, if the 230vac is 3 phase then I might want to consider a separate panel.

I believe American households receive dual voltage supply because some appliances require different voltages , If you tap a phase on a 3 phase supply supply you also get a different voltage. Electricity is dangerous . Combing it into one distribution bov will be regulated by law - get a copy of the law of your country

The concept is certainly allowed by IEC, the execution (which we really can't see) will determine if you get the certification.

What we need to know is if the power sources are separately derived? And just what is the configuration of the power sources, such as are any parts of the supply circuits intentionally earthed?

This seems unnecessarily complicated as compared with a standard single panelboard that provides for both 220V and 110V circuits, where you have the option of placing 220V circuits all together, on one side or the other, or organize them into functional groups, with 110V circuits.

So to build something perhaps new, as opposed to just bolting two individual panels together, we might ask, why?

Why it wouldn`t be permitted? It is made to be used in USA where is 110VAC and in Europe where is 220-230VAC. I have a small old TV that have 220-230VAC and 12VDC switch, so you can power it up by car battery!