@heckflosse, I forgot to point out that part of my confusion came from the behaviour of the lockable color picker: it allegedly works using the rendered histogram which, in turn, is influenced by a button you mentioned earlier:
“If enabled, the working profile is used for rendering the main histogram and the navigator panel, otherwise the gamma-corrected output profile is used.”
I feel the pieces of the puzzle fall into place now.
Hopefully this helps other folks too !