The rough floor plan in my opinion does not deserve rejection, even though I also had to smile at the pantry access. I sincerely wish everyone without envy the money to spend on a basement that is neither required by the property nor by the need. It is essentially the two mentioned points that would disturb my trust in the general contractor here. I have been reading floor plans for over forty years, as if they were poems. The staircase is simply drawn confusingly here, and if the staircase builders are as irritated by this as I am, then I would be inclined to monitor the construction execution* extremely closely, to put it mildly. Together with the generous "all you can eat" stone thickness (typical for M.A.S.S.I.V. builders who want to show "you really get good value for your money") and which is simply questionable in the upper floor as well, this sets off alarm bells for me overall. At least you should painstakingly search the construction service description for what is not included there. But if by chance you are the right client base for this type of general contractor, then it can just as well become a successful project for you and in the end, you will wonder why the grumpy uncle 11ant unnecessarily emitted his pessimistic hand-wringing. You might want to google (including the quotation marks) "lightweight walls in solid houses" and "plan change: from a concrete ceiling to a wooden ceiling." Either that changes your perspective, or you discard my advice (but still think carefully again about the kitchen planning including the passages).
*) General contractors who pass on thicker walls at cost price are, according to experience, the same ones who try to pull the wool over the eyes of the construction-supervising expert when it comes to the proper execution of sealing connections (and where you pay triple for construction water, construction electricity, construction waste disposal, etc., which looked so great in the budget in the offer). There are simply certain "bestsellers" among the cheap tricks to come across as a particularly solid and value-strong construction contractor. Thick stones from controlled organic German cultivation for every little wall are just one of them and already suffice for a certain target group to do without an external site manager or to order one too rarely.