Log cabin bungalow

We have now spoken with our construction company and if we leave out the [dachausbau] and move the rooms downstairs, we come to a price that everyone agrees on.

Construction company? You mean representatives of log houses? By the way, I believe you can achieve a similar indoor climate with brick, clay plaster, and open wooden beam ceilings. But well - to each their own :D
Bungalow with 140 m² cheaper than a gable roof house with 140 m²? I would be at least a bit skeptical, I think.
Take a very close look at the scope of services, what needs to be done on site, what is included - you don't want a nasty surprise where you have to do the foundation slab yourself, or you have to rent the heating, or such nonsense.

It is not a representative. We are building with Natura Holzbau who are around the corner from us and they build turnkey.

It is not a representative. We are building with Natura Holzbau who are around the corner from us and they build turnkey

There is a world of difference between your first post and the last. The initial post sounds like a non-binding inquiry – you would think the plot doesn't even exist yet.

Now comes the information that you already have the company with which you or your parents want to build. You have already made a decision. So I also assume that the plot is already available and all other companies have been explored?!

I have now taken a look at "your" company and its website: I would be surprised if they don’t employ an architect who will design an appealing house for you. They don’t just have model houses, they also build custom.

A bungalow for 4 people should not be a problem for an architect, yet I still doubt that it will be cheaper ;) But, if he says so?!