From a message you made a few posts ago, it *was* working, correct? We are planning on implementing the changes we noted above, as there definitely was an issue with saving cover photos that would have affected sites not using the default tmp directory. From your post above, it sounded like you had things going though, and we weren't planning a lot more testing with Amazon S3 storage for those avatars.
In general, EasySocial and JomSocial handle S3 avatars the same way.. they are first uploaded locally and then (via the cron job) are pushed to S3 when possible. JFBConnect normally doesn't need to care about where the images are stored since we take care of getting them local, and those extensions 'push' them to S3 on their own without our intervention.
So, keep me posted if you were incorrect before, as that will help us narrow down where something may be going wrong. v5.2.2 is scheduled for release later this week (likely on Friday). We may be able to try some S3 testing before then, but not sure if it will be part of this release.
Thanks,
Alex