Featherine Augustus Aurora is portrayed in 'Umineko no Naku Koro ni' as basically the ultimate meta-presence — she reads, writes, strolls through books, and sits above the theatrical stage where stories play out. In canon she demonstrates near-omniscience inside the meta-layer: she knows the structure of narratives, the identities of characters across worlds, and can observe and comment on events as if flipping through volumes in the Endless Library. She literally treats universes as books; that library is where she stores and edits stories, and she can summon or shelve whole narratives.
That said, the series is clear that most of her most godlike acts happen on the meta-plane. Her authorial powers let her create, delete, and rearrange elements of a fictional world, converse with other high-level
witches, and manipulate the rules of the gameboard — but she often refrains from bluntly overriding human will. She plays by a kind of theatrical etiquette: other
powerful beings (like Bernkastel and Lambdadelta) can oppose her, and there are narrative constraints and bargains that make her choices complex. I love how that balance keeps her from becoming a boring, omnipotent deus ex machina; she’s more of an amused librarian-god who delights in letting stories breathe, and I find that restraint oddly comforting.