180 sqm non-replacement house, best adaptation to the plot?

You can't sugarcoat everything.

From which I conclude that idea 4/"diagonal" from your point of view belongs in the discard pile?

I would then like to return once again to the basic topic, orientation on the property:

If you open the house along 13 meters length to the southeast, and exactly towards the southeastern neighbor on the full "wide side." At the same time, however, this is from the street view a classic southwest and not a southeast property, moreover one with an unobstructable southwest location facing the park.
Shouldn't one therefore also consider a solution that is more park-oriented and southwest- instead of southeast-oriented?

I would take the south-west direction towards the park

From what I conclude, idea 4/"diagonal" belongs in the discard pile from your point of view?

It will not be a Hundertwasser.

I think you need to find an architect who uses unusual shapes and materials. Otherwise, it will quickly come across as "not skilled" or "showy and blocky." It should become homogeneous.

The slanted window front in the single room [...] avoids the horrible feeling of being enclosed at a right angle,

Reval or Gauloises are not what you are smoking. At least I have not yet been reached by the Er-bmw-tail light, what except dadaistic arbitrariness is supposed to be behind the boldly slanted wall alignment. For my part, I will now call the so far only "legibly drawn" design the fourth – as long as I don’t even understand the other three, I won’t be able to help you much with the evaluation (and will probably first just go and practically buy some rolls – at least then you know what you have).

It's not Reval or Gauloises that you're smoking

Excuse me?

In this forum, people seek advice on many questions related to their home construction. In the vast majority of cases, they receive excellent advice; often, a precise line of questioning already helps. Some give more than 3,000 — usually valuable — pieces of advice or help with posts. That is valuable for most of those seeking advice. Every original poster also knows that what he/she presents here may be rigorously questioned and "shot down." That is unquestionably acceptable because it is purposeful, since it concerns the factual issue.

Nothing, however, justifies anyone — and this applies entirely regardless of the number of posts, whether 3, 30, or 3,000 per year — becoming personal and disparaging not the design but its creator, using words that the person concerned would not dare to throw at the other in real, personal life.

It's not Reval or Gauloises that you're smoking.

Such wording, which personally attacks others, is out of place in this forum. I have not experienced anything like this in the past three decades, and no one needs to accept this here, just because it happens in the comfortable anonymity of the forum.