Rafter roof instead of purlin roof without inquiry

Hello,

the following rather bold problem:

I have purchased a semi-detached house and for some reason the planner/static engineer of both halves did not grasp the context. So he apparently planned a purlin roof for me (with two main purlins, that is) and a rafter roof for the dear neighbor woman.

Now, throughout the entire building planning, I always signed for a purlin roof (even though it was not important to me, I did find it nice to have two visible purlins in the attic...). Meanwhile, the roof is finished and only at some point did I notice the absence of the purlins. I was never informed about this.

So now briefly my question: Do I have any disadvantages beyond the (visual) ones? How do I best negotiate with the builder regarding a refund (which should be justified if the house is not built according to my specifications)? And what amount seems realistic there?

Are there further problems, possibly of a static nature?

If a picture of the purlin roof planning is needed, I can attach it.

Thanks for your help (: