Selling new construction after receiving funding / Wohnriester - possible?

Dear Kati, I have completely followed your ordeal here (also in the garden thread). I mean ordeal seriously and not ironically. I find it very terrible what you have to go through.
Nevertheless, if I were in your place, I would take a deep look inside myself again.
Who or what gives you the guarantee that it will be better in the new home?
You will not be able to choose your neighbors anywhere, nor know in advance what awaits you.

Here in our immediate neighborhood, we have a very similar case.
They built new just like us. Moved in half a year earlier. Their neighbor is also so inconsiderate. In this case no music, but constantly many visitors on the terrace in the evenings with loud laughter (there is this kind of laughter that drives you crazy if you hear it constantly). The guy is the type "it’s carnival (we’re in Bonn, the stronghold), so I will blast the whole street with loud carnival music from Women’s Carnival Night to Rose Monday because I can’t celebrate anywhere else due to Corona". The guy has visitors all the time. During that time he stood with his visitors in front of the house until late at night with his jester’s cap and “entertained” the entire neighborhood.
The other family has two small children. Apparently they couldn’t sleep for months. Meanwhile, we have repeatedly noticed how loudly they argued so everyone could hear it. Police or regulatory office was on site. The guy is obviously not very reasonable. Corona rules not observed? Fine? Don’t care, I pay. It’s my right. Kiss my ass.
Very difficult situation.

Then we heard that they, like you, considered selling the newly built house.
Because of this guy!

Now we could observe how they built a gabion fence towards their neighbor. It has also been noticeably quiet with the guy for some time.
Was a lawyer possibly involved? No idea.

What I want to say is: you have no guarantee that it will be different or better elsewhere.
I would rather break off with the neighbor and take the risk that the relationship is ruined for the future. I have experienced that myself.
But give up my hard-earned life dream because some idiot shows no consideration?
Never.

On top of that, I fear the chance of finding a farmhouse with fiber optic that stands completely alone, without possibly disturbing neighbors and that is also affordable... is close to zero.

Seek the conversation. Constructively. If that doesn’t work, then have the facts objectively examined. And if necessary, then let it come down to a legal decision.
But give up my “life dream” for neighborhood love?

Never.

Above all, one should free oneself from the idea in the village that one is free from music noise there, even at a detached farmhouse. The local village youth often set up a party hut and then there is often a lot going on and especially loud music. Usually, houses are not built in the village center but on the outskirts or further out. In times of Corona, there has been more going on in that area around here than before. If newcomers take action against it, they often also have the anger of the old residents against them.

Well, it probably comes down to live and let live. I also follow Kati's story on the sidelines, but what kind of extent of noise we are talking about is not clear to me. That would be interesting to know in order to assess the situation.

I don’t want to go off on a tangent, and I don’t even know how to describe the extent of the noise disturbance. For others, it would probably be acceptable. On weekends, I constantly walk around the house angry because I would like to take a bath and cannot enjoy a relaxing bath in my own four walls because I am time-restricted by others – bath? Only if the neighbor cooperates.
I have no desire for this on a permanent basis. Legal recourse against it? Probably none either. As one can see here in the forum, the "average citizen" has significantly fewer problems with it.
Therefore – and this is initially just ONE THOUGHT – we are considering what we would need to pay attention to IF we were to sell the house. That would of course be under the assumption that we found an alternative property that is financially feasible and meets our requirements.
And there we would make sure to be far enough away from ANY neighbors and that the property is large enough to completely avoid the risk of another problematic neighborhood.
Has anyone had experience with this? Selling a house with subsidies / KFW shortly after construction again, for whatever reasons, and purchasing new property elsewhere?

I don't want to digress any further, I also don't know how to describe the extent of the noise disturbance. For others, it would certainly be acceptable. I walk around the house angrily all weekend because I would like to take a bath and I cannot take a relaxing bath in my own four walls because I am time-controlled by others – bath? Only if the neighbor cooperates. I have no desire for this on a permanent basis. Legal recourse against it? Probably none either. As you can see here in the forum, "the average citizen" has significantly less trouble with it. Therefore – and this is initially just ONE THOUGHT – we are considering what we would have to pay attention to SHOULD we want to sell the house. That would of course be under the assumption that we find an alternative property that is financially feasible and meets our requirements. And there we would certainly make sure that we are far enough away from ANY neighbors and that the property is large enough to completely avoid the risk of the next problematic neighborhood. Has anyone ever had experience with this? Selling a house with subsidies / KFW shortly after construction again, for whatever reasons, and acquiring new property elsewhere?

I believe most people here just want to avoid a misfortune born from their biased perspective. Very few here deny how much they suffer. But it is clear that no one here can really answer your question posed in the last post. Everyone here can only express their (!) opinion about the situation. And that is of course subjective. If you really want to take this step and these questions need to be answered (which they should), then you need appropriate legal advice and not a forum, which in countless questions proves to be more than helpful but mostly only possesses lay knowledge.

Legal recourse against it? Probably none either.

Actually yes, but you already mentioned that you didn’t want to go that route.