Thank you for your answers.
I just realized that my question was a bit misleading, but since your answer gave me new questions - lets clarify those first.
So far we used the colorchecker values from the AMPAS github reference images. I just compared those values with the values the gizmo is giving me. Unfortunately they are not matching:
The chart in the background is the one from AMPAS, the inner squares are from the Gizmo. Both in ACES2065-1 and viewed through the Rec709 ODT.
I don't understand that point. I thought if we are working with linear data, then it should not make any difference at which brightness value we are "leveling". Because, well, it is linear... am I missing something?
This page is always open in my browser!
Ok, let me try to ask my basic question in a different way:
I want bring in a perfectly neutral gray patch at 50% brightness into my ACES scene. And I am searching for the right transform to do that in an intuitive way. So I can reproduce the transform in Nuke, Maya etc.