The Elga itself has a regulation that can determine how hot the water should be and when the boiler should be switched on. The Elga only looks at the set room temperature of the thermostat for this. The Elga then ignores the requested water temperature from the thermostat. That is why the advice of Techneco/Remeha is to switch off dip switch B2 with Anna (ignore what the thermostat asks, but calculate it yourself).
The Anna therefore only sends the set temperature to the Elga. The Elga decides for itself how much is modulated and when the boiler has to step in.