Sealing the base of the exterior facade at floor-to-ceiling windows

No, that's nonsense - so additionally bubble wrap.

Yes, it was done the same way with us. The dimpled membrane protects the actual building waterproofing against damage, for example from sharp stones that are pressed against it during compaction.

That's what the EPDM membrane does here.

So is that actually the problem? The EPDM foil is exposed and could be damaged by the gravel and thus become leaky? Ergo, it would have to be placed under the stud foil if at all? Attaching it to the wall seems rather difficult to me right now, since everything is already glued. On the other hand, I wonder what the difference is whether the foil is glued underneath the insulation on the masonry or whether it lies above and is glued here? The sealing of the wooden frame is ensured in both cases, right?

The insulation itself can, however, be bypassed...

Ok, makes sense. Keep researching how I should proceed here, thanks for the info! Definitely already!