TGA planner difficulties, underfloor heating supply temperature + wastewater ventilation

To my knowledge yes, although one does not know whether the developer chose an underfloor heating installation pipe with poor bending properties due to cost constraints, and whether this is communicated in the technical data sheets that should be available to the HVAC planner.
Here, as mentioned, it would be important to inform the developer that one is willing to bear the additional effort and material costs.
Warning, this can lead to very high costs with many HVAC planning offices. Not everyone bills like the universally popular DI Heckmann here with a few hundred EUR, but average HVAC offices want 2-4 thousand EUR for a simple single-family house planning without planning according to DIN, possibly even more.
Then there would be the increased material costs, which, in the constellation of developer and sub-sanitary, certainly would not remain below 1000 EUR either.

But try it, maybe it won’t be that bad.

I have already had that experience. The TGA planner demands a whole lot of money for his previously extremely poor performance. Of course, the developer doesn't care at first, because he doesn't have to pay for it. Let's see if anything can still be done, it would just be a shame not to at least try. And just for understanding: You consider it possible to run 40° warm water through the pipes without the surface temperature exceeding 27°C?