Window & door installation not compliant with standards

If KFW means nothing to you, you probably don't have a loan from them and consequently no funding. Then (presumably) no Blower-Door-Test is necessary, which would have revealed leaks.

The OP is from Austria - there is no KfW there

Our wooden house on a concrete base was initially something our architect also wanted to "sell" to us. But thanks to the infeasibility on the part of the concrete builder (the base would be so narrow that laterally attached angles would have "exploded" the base, costs too high, waiting time too long due to multiple formworkings etc.) it didn’t happen. The outer walls will be wrapped in foil in the lower area up to a height of about 30cm (in case moisture should ever penetrate to the wood). With Purenit, a base made of mineral insulation is probably meant that the window/door builder should offer. This is water-resistant, rot-resistant, and so on. It is often not included in the standard offer so that it can then be charged separately (since necessary). Presumably, a larch base means a board in the door area that only serves to prevent the screed from running away.

A wooden base on the ground floor in the door area? No go, never ever. Would be too risky for me unless the house stands very high and there are 2-3 steps leading into the house (compared to GOK).

If water damage occurs there, it can only be repaired with an extreme effort (costs). No compromises here. Get advice from a professional (doesn’t he also have liability for correct installation?). You really don’t seriously want to install the €7000 door yourself?

As a homebuilder, one should actually have read the term KfW at least once; it can be about a lot of money. So always consider it as an option... Also BAFA and ProgressNRW... (if in NRW) etc.

Architect? Energy consultant? Site manager?

Construction is much more complex than you first think (at least for me). I’m glad I don’t have to plan everything alone. Fortunately, we have many companies, an architect, the home builder, etc., who all use their heads, and so far I have a very good “gut feeling” about all of them.

I wish you luck and a bit more assertiveness so that your construction still ends well. A lasting conflict with your husband, father-in-law, etc. would of course also not be nice, so insist on an independent third party (expert?)

If the windows are properly installed and foamed, I don't find it catastrophic that no sealing tape was used. The old gentlemen are somewhat right; if you seal everything completely, you basically have to install a ventilation system. You haven't mentioned anything about that. If it really bothers you that much, the windows can of course be removed and installed again with sealing tape. Scraping off the foam will take some work, but it is doable. Of course, painting will have to be done again afterwards. Maybe you’ll do that when a round of painting is due a few years after moving in.

But I would definitely skip the wooden base under the 7000€ front door. As you and everyone else say, that is an unnecessary risk. If even a hint of moisture gets on it, it's only a matter of time before problems arise. Putting something solid in there shouldn't be a problem, so you need to insist on that now.

Pictures would be fantastic to assess this.

As a homeowner, you should actually have read the term KfW at some point; this can potentially involve a lot of money. So always consider it as an option ... Also BAFA and ProgressNRW ... (if in NRW) etc.

As already pointed out, the OP comes from "OE," which in this forum does not mean Olpe in NRW/DE, but Austria (which itself consists of several federal states, but the admin in CH probably doesn't care). The KfW (Kreditanstalt für Wiederaufbau) is a German federal-state institution created for the implementation of the Marshall Plan, which, like the sparkling wine tax, just continues to exist forever – but Austria was already separated from the German Reich during the Marshall Plan.