Thanks, @walt.farell - I think it is a very crude workaround actually that hard to understand and use that I can hardly believe that it is an intentional implementation, but it works. I describe, how I use it for my dual lingual thing: On my (one and only) masterpage I create two empty layers, text_E and text_D. Than I go to every page (only need to do this once, and If I had known this before, I would have created pages like this), right click the masterpage in the layers panel, click 'Edit Detached' and than move my Text elements (both switched on!) into the refering layers on the masterpage, so they are grouped underneath them. Than I finish editing detached (by clicking the 'finish' button in the red window banner, that appears, while editing the masterpage). If I than go to the masterpage, and switch on or off those Text layers there, this is applied to all pages, where I subordinated them into the masterpage elements. That layers, that are empty on the masterpage, but contain different elements on the individual pages, work like 'global layers'.
So this works. This means: technical there is something like 'global layers', so it should be possible, to change, how these are implemented. I think a first step could be, to allow the subordinating of layers (that I would see as 'objects') into these previously empty layer groups on the masterpage (that I would see as 'layers'), without the need to do that 'edit detached' thing. I do not see a danger to change something accidentally than, as the changes even now do not effect back to the masterpage but only on that one page, making it 'globally structurable'.
Actually I do not see the reason to have individual page layers at all in a layout app, there could be a kind of 'default' layer in the masterpage, where all these are subordinated (that could be 'unswitchable', If there is a need to prevent confusing accidental use)
Rolf
But yes, masterpages can do the job, it is only far from intentional, how to use it.