Are the admins of lemmy.world somehow responsible for what their members do, even if it´s not on their own instance?
They are not responsible for what their users do, but for what is saved on their instance. And by any lemmy.world user interacting with content from a different instance, their lemmy.world will host a copy of that content. That’s how lemmy works.
So if a lemmy.world user subscribes to a pirate sub, that whole subs content is now mirrored on lemmy.world.
Not just related to piracy that’s a huge liability issue for admins.