Localisation / Naming of Devices/Entities/Classes

So, im setting up Homeassistant new from a scratch.
I want configure HA in English, but in order to use assist later, i want all my Device Names, Attributes to be in my native Language (German). However, when setting it up, i want the entities to be technical/english.

So, e.g.:
environment_hallway_01
sensor.environment_hallway_01_temperature
sensor.environment_hallway_01_humidity

Device Name: Flur
Friendly Name: Temperatur

How do i do this, what is necessary?
It looks like HA translates SOME, but not ALL Attributes. E.g. an older Aqara-Sensor set up with Z2M while HA beeing English, now after setting both System language and User Language shows “Temperatur” and “Luftfeuchtigkeit” as well (Quite sure System-Language been english, userlanguage only 90% sure english as well).

However, other Devices at the same time show up with English Attribute Friendly Names (e.g. Tasmota Plug ENERGY Power, ENERGY Today.

Now is the time where i enroll all my devices again.
How Should HomeAssistant/Z2M, maybe even my laptop, be set up while adding device, how do i set it up later, in order to achive the desired setup described above?