Honest question: If a federated community is conceptually acting as a single community, why should moderators be limited to the side corresponding to their instance? At that point, wouldn’t there be a unified ruleset for the federated community that is separate from the rules of the hosting instances?
I get that not all instances would abide by the same rules, but I reckon that if you want to keep a federated community, you also need to make sure to comply with all instances or risk some instance from removing their community from the federation.