Moisture seeps through the floor-to-ceiling windows in the new building

That is ideal. But I think if you apply it over the insulation, nothing will happen either. Of course, only if you don't have groundwater. Because of the drainage, it is often done this way. Our expert said that would be okay, but not according to DIN..

How is it usually sealed above the insulation so that nothing gets between the liquid plastic and the insulation? I still have to do that too. Also with liquid plastic? I roughly sketched it in the attachment (I mean the red part). Is liquid plastic also used here or just a smooth coat with concrete?

[ATTACH alt="Aufbau_bod_Fenster.png"]56330[/ATTACH]

You drew it correctly. To do it according to the perimeter insulation, the insulation must definitely be removed at the gap between the window and the concrete ceiling. Then you seal from about 30cm down (yellow). The small piece of insulation in front of the window is then glued back on.

At least the insulation on the side of the basement can then stay there. The important thing is the gap, it must be properly sealed.

I meant how the red part is sealed. I have the liquid plastic seal (green in the picture) behind the insulation. But now there has to be something additionally over the insulation (red in the picture) so that nothing can get between the liquid plastic seal and the insulation?!

So, if water gets in between the insulation and the liquid plastic, that's not a problem?