Floor plan design single-family house 1.5 stories without basement approx. 160 sqm

This is initially just a rough draft, We wanted to take the draft to the surrounding timber construction companies and get offers. [...] Exterior walls are not yet precisely drawn. Since it is timber frame construction with clinker facade, it will be about 450mm. [...] My concern was whether there are any major errors in the plan.

Starting orientation offer requests with a preliminary draft is an approach I also recommend. That it is a preliminary draft, I must have overlooked ;-) and it is also not practical to already present it in design scale. Even less sensible is to plan a wooden house in a stone construction system – from my point of view, that would already be a "major enough error." Furthermore, while I do recommend regional suppliers, I expressly limit this recommendation to the Steiners. The "surrounding timber construction companies" are regularly still at the industrial maturity level of the large "prefabricated" house manufacturers from exactly the time when the cardboard box prejudice was valid.

P.S.: If you are going to gather orientation offers anyway, you could have spared yourself the final drawing by the draftsman - that can be done with DIY drawings (even napkin scribbles!) at least just as well.
By the way, I also recommend that you send these inquiries in a construction-method-open way to a mixed handful of wood and stone builders yourself, even if you already have a preference.

I don't see the problem with too few windows as critical, especially downstairs there are really many windows. However, in the bedrooms, you could reconsider that. Maybe also think about whether you would prefer a fixed glazing behind the sofa, etc. That would save you some money and you would never open those windows anyway. If a controlled residential ventilation system is planned anyway and you can ventilate by opening windows on two opposite sides, then that is basically sufficient.

At the bottom right of the plans, you can also see your full name and address. Not a big deal, but just so you have that on your radar.

At first glance, I don't think the dining nook in the kitchen works. If the chair is not pushed in correctly, there is no passage to the living room anymore. Why should two dining areas be created in a small house? The space would be better used elsewhere.

I am also surprised by the orientation with the driveway in the southwest. You can see with both(!) neighbors that it is usually planned more in the east to have afternoon/evening sun in the living rooms.

Similar to the neighbor on the right, I would also look for a concept and plan the parking space detached south of the house with a short driveway (like the neighbor at number 13). Even if the left neighbor apparently likes castle-like driveways. If you go one plot further to the right than shown, you can also see that the indicated building lines do not seem to exist. So other house positions on the plot would definitely be possible.

For the kitchen with a room width of 312, it is neither one thing nor the other, you cannot place a peninsula, and the dining area does not make it any better.

For a two-row kitchen, the kitchen is unnecessarily wide, for any island solution it is too narrow. Just measure a bit at home.

Where is the wardrobe?

At first glance, I don't think the dining nook in the kitchen works. If the chair is not pushed in correctly, there is no passage to the living room anymore. Why should a small house necessarily have 2 dining areas? The space would be better used elsewhere.

For a two-row kitchen, it is unnecessarily wide, for some kind of island solution it is too narrow. Just measure a bit at home. Where is the wardrobe?

Both are valid objections. I recommend to the OP to now make the intended orientation inquiry (as said, mixed to a handful of providers, e.g., three Holzer and two Steiner) and after their feedback (and thus the result, whether one can afford the desired size or if it has to be smaller) to incorporate the improvement suggestions.