The building application is always submitted by the builder. It is prepared by the architect.
Exactly. And in the case of the prefab house guy, the architect is typically the included draftsman. But the OP should have that explained by his lawyer. If it says "legally read" that he has to "drag the house supplier to court," if he signed it that way, then unfortunately that’s how it is—no matter how unrealistic it may be. Especially the "prefab" builder is typically the textbook amateur who needs the "fire and forget" full service (and will usually also be orally and worthless promised "You sign, the rest will be taken care of calmly by us" by the sales representative).
Maybe Okal Haus wants assurance that access with their construction vehicles (mobile crane, semi-trailer, ...) is possible and permitted?
Exactly this fundamental buildability (hedge torn down to the required width, ditch allowed to be crossed by heavy trucks, etc.) has to be clarified first—and even where there are no special conditions at all, a supplier will always hide behind not having yet checked off the explicit all-clear for this! (especially if they have given any delivery time commitments, where the fine print is ALWAYS the most important).
As it seems to me, the OP simply overlooked "Paragraph 1 of the unwritten general building terms and conditions," which reads: 1. READ
everything very carefully BEFORE SIGNING to know what
obligations you have under the contract, because 2. at the moment you sign, WITHOUT EXCEPTION ALL SELLER’S TALK IMMEDIATELY LOSES ITS VALIDITY!
(Sentence 2 in legal jargon means: "
there are no oral side agreements" = talk is disappearing ink!)