Just an update on this. Looks like we're still on schedule. CB Activity 4.2.1 released and CB Auto Actions 7.2.0 should be ready for next week followed by PHP 7.2 testing and fixes.
A build release for CB Auto Actions 7.2.0 has already been released as of today and contains some new improvements for activity grouping. Activity grouping allows the assets of 1 activity to be attached to another activity. What this prevents is storing tons of activity for same/similar activity. Currently if you upload 100 photos in CB Gallery that's 100 activity entries. With this new grouping feature it now generates 1 activity entry and attaches the other 99 would-be activity assets to it. CB Gallery can then parse those out fine. This requires latest builds for CB Activity, CB Auto Actions, and CB Gallery to utilize, but you should see performance gains going forward where gallery activity is involved.