Hi, Fred let me know about this thread and I would just like to add some detail on this topic.
ACES 1.3 is the current release and the only new feature it contains is a gamut compression algorithm that is useful to prevent colored lights (e.g. from a police car) from clipping in the ACES Output Transforms. There is a Matchbox script for a development version of this algorithm (there were some changes in the final version, but this gives you a close approximation) here: GitHub - jedypod/gamut-compress: Tools to compress out of gamut colors back into gamut.
ACES 1.2 added version 3 of the Common LUT Format (CLF) and the ACES Metadata File. Flame supports version 2 of CLF.
ACES 1.1 was the most recent release that introduced new color transforms and Flame has supported that for several years. So if you just need the current versions of the color transforms, Flame already has that.
Doug Walker
Autodesk