Questions about hydraulic balancing

Hello,
I am currently in the process of balancing our heating system, end-of-terrace house, KfW55, net living area 145m², Vaillant Arotherm 75/5. I think I have understood the basic principle behind it, but I stumbled over two points.

The heating output on the ground floor was generally too high. I initially reduced the flow rate slightly on all circuits here. It was also easy to see that reducing the flow rate in one heating circuit increased the flow rate in others. That makes sense, of course. However, I assumed that this would also affect the flow rate in the heating circuit distributor on the upper floor. But it does not. Am I mistaken here? Is the flow rate to be set separately for each heating circuit distributor? In the master bathroom (upper floor), I currently have about 1.6 l set on the Taco, which is also the maximum adjustable value in the current configuration; I cannot open it further. I would like to try whether 2-2.5 l might bring somewhat higher temperatures.

Is it correct that the sum of all flow rates should roughly correspond to the flow rate of the pump on the Arotherm?

One has a room-by-room heating load calculation carried out and calculates the flow rates based on this. Everything else is nonsense,

Was done by the developer, the heating engineer said "this is shit", did it differently (better) and set roughly 1.5 l/m on all heating circuits on the ground floor and about 1 l/m upstairs. So much for the work of the professionals!

Was done by the developer, the heating engineer said "this is crap," did it differently (better) and set roughly 1.5 l/m on all heating circuits on the ground floor and about 1 l/m on the upper floor. So much for the work of the professionals!

Help me out: what do "1.5 liters per meter" respectively 1 liter per meter – that is l/m – define??

It should have said 1.5 l/min, sorry. Normal flow meters/Tacos are installed with a scale from 0 - 5 l/min.