Thermostat normally closed (NC) or normally open (NO)

Why give up? What do you mean by that?

In forums on the web, people generally use the informal "you," a "Sie" is not necessary there ;)

Of course, there are different opinions about this. If you have done a proper hydraulic balancing, it is not necessary to use actuators (and thus also room thermostats). Through the hydraulic balancing, you regulate the flow rates in the rooms so that the desired temperature sets itself automatically. This saves you the electricity for operation and usually leads to a more even and efficient operation of the heating system (especially with a heat pump).

P.S.: My Cosmo actuators have a manual function. I simply unplugged them and manually turned them fully open.