Can someone read or understand this flyer?

Comfort climate heating equals air-to-air heat pump like Proxon etc., so without water-carrying heating surfaces and that in a KFW 55 house... Kfw 40+ or passive house maybe ok but in a KFW 55 never ever... Take the flyer and throw it away...

It would also be a reason for me to distance myself from the provider altogether.

I would find mutual fairness important. Small regional GUs also get by well without flashy gimmicks and build good houses. A house is unfortunately not a purchase item, but a project.

I would clearly advise the OP to buy an existing property.

The term "finished" house never means "just swipe the card and turn the ignition key" (that also exists, but is called an existing property), but actually a "prefabricated" house, meaning less visible working time spent on the plot. Nothing goes faster there, nothing is more predictable either.

The gap between the value of the offer and the seller's price expectation is smaller the younger the house is – however, you buy the young used house from a different market channel, ideally from a divorce lawyer. If it may be older, then the undertaker is the best connection. On the other hand, those who search through an agent are most likely to find unattractive offers price-wise: agents are engaged when sellers are crazy and don’t want to believe it. The typical disagreement usually lies where the seller values a feature based on its original high quality, instead of calculating like the buyer does (namely: quality is practically irrelevant when the stuff is screamingly outdated, then it basically has the time residual value "zero" minus the costs of removal).

Meaning: the perception that "existing properties are often a joke price-wise" has trivial reasons (which apply most strongly to the object age class "no longer fresh in taste, but not yet substantially in need of renovation"). However: the bolt staircase will come back.

Existing properties score with the best calculability, but pitfalls lurk here as well, e.g., waiting time bombs like local fees. In new development areas, on the other hand, people are pleased about views built in the next construction phase or about streets after whose completion the plot lies in a basin.

I was more referring to the boundary condition that the original poster (as I understand it) would like to choose a house from the catalog, then have 1 year of peace until the house is finished and he can move in.
Building a house is quite stressful, especially when you live 300 km away.

And "prefabricated house" does not mean that it is ready in the sense that you can move in right at handover. Much more, the term refers to the construction method using prefabricated parts, which are manufactured somewhere in a factory and assembled on the construction site. As opposed to the solid construction method "stone on stone". In both cases, for example, "turnkey" (usually at least floor and wall coverings still need to be done or contracted) or "ready to move in" is offered. The latter would probably be what you mean?

Oh interesting, thanks! What does GU mean? Where can I find someone like that in the greater Hildesheim area? Even if it makes people cringe here, for us "ready to move in" would be wonderful.

What you are looking for you will not get with a general contractor (GU). The builder has to take care of many things themselves. Some things can be delegated to the GU, but not everything.
The term prefabricated house refers to the construction type: prefabrication. And of course on a builder-organized foundation slab. There are additional incidental construction costs related to the plot, also organized and paid for by the builder, such as utility connections. Usually, "turnkey" does not mean move-in ready, because painting work and floor coverings still have to be done independently. Painting work does not only refer to walls but often to the entire wood treatment including the stairs or the exterior base finish.
Then there’s the outdoor area like paving and so on...
Pay attention to the scope of services description from the house builders: often they are not standard what one would like, for example the electrical installation, which has remained at a 1970s standard even though one needs a lot more sockets, etc. -> extra costs.

Who offers what you want? A property developer who sells the land and the house together. Then you are not builders, but buyers. That is often spoken of negatively, but in individual cases like yours it is the most sensible.
Or a used property: as seen, so bought. But one usually has to be willing to make compromises in some things, mostly regarding the fittings.
Compromise is also necessary for plots: many want a two-story city villa, but the development plan allows something else.
Building a house is not something to be done easily between two moves. And building a house is not always sensible.
A tip for Lower Saxony: Viebrockhaus, who build within 3 months, offer AI, but demand quite a bit of money for that. You have to like their concept though.

In Hildesheim there are planned semi-detached houses and terraced houses from developers. I would take a look at that, or rather, I would consider any affordable house from around 2005 onwards and take a closer look at everything, not dismiss it immediately. But personally, I would also have no problem with a terraced house if everything else is to my satisfaction.

By the way, I immediately thought of the blog as well. It is very well known in mom and sewing circles. Just Google MamaHoch2.