Converting hdr to ACES

Hi, I also quickly download the HDRI and the Checkerboard as lin_sRGB.

When I balance the colorchecker down to the ACEScg 18% grey and overlay the values I get this result

The greyscale seems a bit off - and how am I suppose to compare this to the values in the actual HDRI? They are not the same exposure, that is strange.

Greetings

Daniel