Underfloor heating - How to insulate the supply lines to the rooms?

. It is simple thermodynamics

Correct. The problem is just that your control requirements, as you have presented them here, conflict with simple thermodynamics. Fast controllability requires high temperatures and preferably little mass. A new building has the opposite in both respects, hence the critical questions. Because of simple thermodynamics. And because of that, some approaches work, but others simply do not.

With underfloor heating at low supply temperature in thick screed, the thermal inertia of the system is longer than the duration of normal control periods.

Isn't it much more likely that you hardly want to heat with the underfloor heating anyway and therefore it somehow does not matter?

It's not about efficiency for him at all. He wants comfort. Comfort costs.
However, I am of the opinion that he doesn't care about the supply lines of the heating circuits. Because if he wants to control all heating circuits anyway with "manual" interventions (meaning not leaving it to thermodynamics, but overriding it, even if this happens automatically through rules), then he can also let the dedicated bedroom heating circuits be throttled if necessary. And when the fireplace is running, everything else is turned off anyway.
Therefore, my recommendation is to rather insulate the bedroom from the other rooms than the 9mm over the supply lines of the "non-room" heating circuits.

summarized it very well. Thank you very much. How and if I will regulate it later is still open, I now have all possibilities for that. In any case, according to my current plan, the open space (about 70 sqm) will be set rather too cold from O to O (winter tire weather). When the tiled stove is heated, the 5 heating circuits in the open space will be turned off. According to our plan, this will already be at 7 a.m. Then a burn-off takes place and the room will be warm enough. Based on the temperature from the thermostats, the underfloor heating will see no need to reopen the heating circuits. In the afternoon, there will be another burn-off and the same process. Ideally, the 5 heating circuits in the open space will be run significantly lower, less flow, less heat. The same applies to the fireplace room. Planned as a guest room, second open space, second office, or playroom. So it is our multifunctional room. Actually the nicest room on the upper floor. Here the room temperature will probably be adjusted so that the room is cooler than the others. The points of contact with the other rooms are also low. It is like a kind of flat roof annex. That means the room is also well thermally separated. Here 2 heating circuits were installed with a 10 cm spacing. This will also be noticed quickly if necessary. However, the fireplace is the focus.

In fact, the bedroom is also very well separated from the rest of the rooms. A wall was built with 17.5 aerated concrete, which should contribute well to insulation. Soundproofing is less good. Actually, sand-lime brick was planned there, our preferred stone for interior walls. Generally, almost all interior walls are 17.5 with lime-cement plaster.

3 heating circuits have now been rerouted in the attic. That looks much better. 3 heating circuits still pass through the bedroom. That is fine. Especially when you had previously seen the additional 12 pipes in a very tight space. Ui Ui.