I don't know of communities, but I know that this exists: https://github.com/chrisliu298/awesome-representation-engineering
Perhaps you could create such a group if you wanted to because such a thing seems interesting? Happy to share the group with people I know who might be interested!
Looking for any discord/slack/other that have people working on projects related to representation reading, control, activation steering with vectors and adapters, ...Would appreciate any pointers if such a thing exists!