Is the district heating consumption at KW 55 house too high?

Where the meter is located is not so important. It must measure the volume flow, in the supply line or in the return line. And at both ends the temperature. The rest is then an integration of the product of volume flow and the temperature difference.

You seem to like calculating. With some effort, you can quite easily calculate how much energy, even without losses, is required to raise your building structure to x degrees. Just roughly as an example: The floor slab and ceiling are about 120,000 kg of concrete. Concrete has a specific heat capacity of 0.88 kJ/kgK. Assuming the house is 12°C before heating and should be raised to 20°C, that makes a ΔT of 8K. Energy = 0.88 x 120000 x 8 = 850MJ, converted to kWh = 250 kWh. And now the same for masonry, screed, plaster... And then at the end, also subtract the losses linearly over time. It adds up.