I would not commit in advance to a fixed number of square meters. Ultimately, there should be no square meter too many, but just as little as none too few. Given your needs, I would also rather see a clever architect work on it than standard floor plans being expanded and thereby often becoming space wasters. I find it problematic to assess equipment solely based on the descriptions "upscale" or "standard," since the difference between standard and standard can easily be 50,000 to 100,000 euros; therefore, you should specify this concretely or make it clear to yourselves what it means for you in detail. In addition, there are things that occur after the sampling like lights, furniture, kitchen, etc. The certainty with which of the mentioned providers you will have fewer problems probably cannot be clarified in advance. I believe that a good architect who recognizes and wants to serve your personal needs as people is also a worthwhile investment.
Therefore the question whether you have ideas who else you could ask.
You can basically ask anyone; I would rather want to find out who is most likely to serve my personal concerns:
where you don't really have to be on the construction site every day to check.
You can save most of the money upfront through clever planning of the house’s location, the floor plans, and avoiding unnecessary areas and expensive special features in the house. How do you come up with 225 square meters? Show your project in detail. It is well known that every square meter saves you at least €3,000, so I would initially focus there rather than on "penny products" like pleated blinds in the interior now.
We are not demanding when it comes to tiles and parquet (and that is already factored in, see above) and a carport is not an option anyway, that is clear to us and is also okay for now. Pleated blinds are an extra we could install later. For the time being, curtains in the bedrooms are enough.
Almost all builders think they don’t have high demands, whatever that means. But with 225 sqm you have already set a costly stake, and from the way I read it, you are already afraid that you might run out of steam in the end. I understand that, so check whether you can reduce your 225-sqm plan without quality loss so that it might still be enough in the end without transitional curtains and pleated blinds or for a carport. I think you took the second step before the first, hence the idea to openly present your project here.