Window sill height 130 in the bedroom / study?

Maybe you could put your before-after option side by side so that everyone here can give an opinion (if you want to). I believe that if you completely detach yourself from the exterior once and draw the windows exactly as they would be perfect for you FROM THE INSIDE, then you certainly wouldn't have a less attractive house either. Just go through the rooms one by one and think about what you want to see from where and how.....we tried endlessly, placing the chair, the lounge, etc., whereas basically we are more inclined to want windows as large as possible. That's how we have it now and we enjoy it. The issue with looking in can be corrected from the inside, e.g. with frosted film or similar, but if looking out is impossible due to too small windows or sill height, no film will help. And......a little doubt will always remain, that's why people build several houses in their lifetime :D

There are always priorities in house construction. With you, , I get the impression that the exterior is particularly important to you. At the same time, you have identified a potential disadvantage for two rooms due to the parapet height.

I find the appearance of the first draft quite successful. As already points out, one can see a number of costly details. That's no problem if the budget is there; there is no law for cost-efficient building. Whether the house also achieves the desired effect depends, to a similar extent as the design of the facades, on the property and surroundings. On a 1000sqm plot, achieving the effect will already be tight, and such a "clean" design requires a suitable exterior landscaping. Also no problem if space, neighborhood, and budget are available for that.

What distinguishes a beautiful house from a beautiful and good house is the way the house brings long-term deep joy to its inhabitants. Of course, both are possible at the same time. Whether you will succeed at that, I cannot say.

Your name suggests a tendency towards high-quality music playback. Therefore, I will try a comparison from this area: You seem to be taking the "Bang & Olufsen" route. Elevated price, stylish design, and the sound is quite alright, but has nothing to do with truly good systems, which already exist in this price range. High-End and design of course also exist in many facets – that then requires a different environment and costs a bit more – whether in the style of Burmester, Gryphon, Wilson Benesh, McIntosh, Naim, Linn, Meridian, or Jadis. I would think more along the lines of Brinkmann, hardly known, elegant, simple, sounds breathtakingly good in the right environment, and is not overpriced. Could fit.

so theoretically I of course know what you want to say with the comparison... but nevertheless, somehow the implementation is still lacking.

I would only install windows with a high sill height where there is a justifiable reason for it. For example, we have several windows at 1.25m: one behind a kitchen unit because we use the windowsill there as additional shelf space, one (we live on a hillside) on the hillside side to intentionally direct the view upwards toward the summit cross, and one in the entrance hall because the staircase runs along the wall and I didn’t want the sill too close to the steps.

Otherwise, as a normal window, it is an absolute no-go: you are always forced to look up, which was rather used by rulers in earlier times to intimidate their subjects. Your view loses contact with the ground, your orientation. It is also dark, because in addition to the sill height there is always 10cm of frame - logically on all four sides. You can have fun calculating the glass surfaces and relating them to the respective room size - it’s not much. Personally, I would have an immediate flight reflex in such a room.
By the way, I find even 90cm sill height (plus 10cm frame!) too high. I can see straight out of my work window (sill height 45cm) what is going on outside. When children come home from school, who is sweeping leaves, occasionally a squirrel, etc. Based on the fall protection, I can tell what I (as a tall sitter!) would see at a sill height of 90cm: none of that.

I can only emphasize the tip that has already been given several times here. Plan it from the INSIDE. Imagine yourselves in the rooms, where and how you will spend time, where you will look, where there are nice views (or the opposite), how the sun moves, etc. Completely leave out the exterior views and fantasize only from the inside about where you want which windows. Sill height, width, corner glazing, etc. are completely free in this process. If you are sure about this (and when in doubt, rather more than less window area), then you draw the desired windows into the exterior views. It can look completely wild:

If you like it, you can keep it. Or you domesticate the whole thing, for example by repeating proportions or formats (which can alternate between portrait and landscape), alignments between ground floor/upper floor, etc. But the important thing is that you think completely freely from the INSIDE during planning. Whether, and how much, you normalize it again for the exterior view is a subsequent step.

About the design itself: in the north rooms (work and child) sill height 45cm is marked on the upper floor plan. But I don’t see it in the elevations. Mistake, or am I confused?

I find the bathrooms unfortunate: on the ground floor it conflicts with the entrance door and hallway, and upstairs it is (too) large and still the bathtub is old-school in the corner. How about moving the staircase to the other side of the hallway (i.e. upwards on the plan), and then partitioning off the right part of the bathroom upstairs (where the bathtub currently is) for a separate toilet room? That could then be accessed directly from the hallway, and you could save the door to the bedroom.

well, I find the example picture completely off... it just doesn't fit our ideas from the outside... which doesn't really make it any easier. Personally, we are not particularly fond of the floor-to-ceiling windows on the upper floor; I could never imagine having something like that in the bathroom. I didn't want to change anything in the floor plan anymore... the front door will be moved to the other side anyway... but that's not what it's about for me. Of course, it's important to me that I have enough light and occasionally a view from above when I want it, and not the other way around, where everyone can stare into my house (where it is not desired). We somehow don't want to have a puzzle of windows on the house.

Of course, it is important to me that I have enough light and occasionally a view from above when I want it

Yes, exactly! In my opinion, you have too little of that now.

not the other way around so that everyone can peek into my house (where it is not wanted)

I would not control that by the position and size of the windows, but through privacy screens inside and especially outside.

We somehow don’t want to have a puzzle of windows on the house.

Why? My wife didn’t want that either; in our case, it coincidentally worked quite well with our other wishes, which is why we are fairly symmetrical. But I didn’t understand that and I would have been totally fine with it. Eventually, I was not allowed to press further with my wife, for the sake of peace in the house. But with you, I dare! Why is the symmetrical or even identical arrangement of the windows on the outside so important, when you yourself are inside?