New construction - now or wait? Experiences?

Filling, sanding, installing interior doors, and mounting sanitary fixtures were all agreed to be handled by Bien-Zenker. Is there an item in the offer where this is not included?!

We only wanted to do the painting and lay the floors ourselves. We feel confident in that and also know a master painter.

We can get the photovoltaic system cheaply through connections.

We had agreed that Bien-Zenker would take care of spackling, sanding, fitting interior doors, and installing sanitary fixtures. Is there an item in the offer where this is not included?!

We only wanted to paint and lay floors. We feel confident doing that ourselves or we know a master painter.

According to the construction service description, it is not included; your contract excerpt does not state that Bien-Zenker takes care of this. Therefore, it is not included or an essential part of the contract is missing.

We had agreed that would take care of filling, sanding, installing interior doors as well as mounting sanitary fixtures. Is there an item in the offer where this is not included?!

I'll ask, as we used to do in law lectures: Where does it say that the full provider is responsible for this?

Visible is the level "ZAF". And that means with the provider that you are responsible for all points. If there are other documents in which different agreements are made, then you have not provided them.

If I follow the current discussion, it began with misinformation about the real estate transfer tax and is now continuing with uncertainties about the construction service description and the scope and effort of the own work. I would like to shout out to the future builders: retreat, familiarize yourselves more with the subject matter and take a break. Under no circumstances sign a contract now.
With our own construction project 7 years ago, we had clarity because of the real estate transfer tax, but then experienced some expensive surprises regarding the construction service description and the necessary additional surveys with the construction company. By the time the house was finally completed including the outdoor facilities and fully furnished, we were at 1.8 times the price that was once stated in the construction contract. (Attention, the 1.8 times also includes the land price) I had feared this from the beginning and only gave the construction company half of my budget at the start. In this respect, it was no drama and we are satisfied with the house.

Is there a point in the offer where this is not included?!

You were pointed out that the construction service description applies. They show you screenshots from the home builder Bien-Zenker – here you yourselves are responsible to read everything.
You only get what is contractually signed.
It seems to me that you rely too much on information given to you rather than doing your own review, research, and verification of prices.
A master painter also costs money. And not a little. Whether he paints during his working hours or forfeits his main vacation for you.

By now, your DinA4 sheet should be filled with some calculable additional costs, which should prompt you to research several topics. And it starts with the real estate transfer tax, followed by issues of different cost presentation and feasibility, but also a bit of contract law.

Again:

Is there a point in the offer where this is not included?!

Is it stated anywhere that it is included?

To be clear: you are completely uninformed and (so far) have no idea. Tear up the contract draft and spend a few months familiarizing yourselves with all relevant topics. After that, you will be capable of commissioning.

Alternatively: increase your credit limits and commission everything the providers promise you without being informed. But that will end up costing you a learning fee.