It is because the CG config inherits from the Reference config that has the RGC (Gamut Compressor) that is only available in OCIO 2.1, changing the profile is perfectly fine and we will certainly need to generate a few more of those with different versions. If you want to report an issue, the best way is to do that on the repository: https://github.com/AcademySoftwareFoundation/OpenColorIO-Config-ACES but it is also fine here! 
It is hard to compare your images here, something worth noting is that OCIO 2 implements ACES analytically, i.e. no LUTs so it is expected to see some differences!
Cheers,
Thomas