Stair stringer partially in front of window - leave stringer open?

Letting it run through is the lesser evil, I would do the same.

This is not about insecurity

I meant: the stuff you still manage to come up with just before the final whistle is quite unique.

I meant: the things you still manage to get done just before the final whistle are really quite unique.

I wouldn’t have thought that either. It just goes to show how valuable good planning/a good architect is from the outset. But you can’t think of everything, and you don’t know everything during the initial planning. Some things only come up during the course of the house construction. The tradespeople also provide a lot of input. It’s good that there are forums like this one.

Is a railing actually going to be installed in front of the window at the stairs? If yes, then hardly anything of the window will be visible, right?

Is a railing going to be installed in front of the window at the staircase? If yes, will hardly anything be visible from the window?

No, there will be no railing installed at that spot. There is only the post on the inside at that location.