Sorry for my late answer and only for the sake of completeness:
I activated the option Send setpoint change:
After that I was able to configure a group address where HA can read the current setpoint temperature from:
After changing that configuration and programming the device the channels stepped into Standby mode and I have had to manually set every channel to comfort-Mode back so that HA can send new current setpoint temperature.
My HA configuration looks like this:
- name: climate_control.bathroom
temperature_address: '12/0/6'
setpoint_shift_address: '7/0/6'
setpoint_shift_mode: 'DPT9002'
target_temperature_state_address: '7/1/6'
setpoint_shift_min: -6
setpoint_shift_max: 6
temperature_step: 0.5
min_temp: 15.0
max_temp: 26.0
In my case the attribute setpoint_shift_mode is crucial.