The definition of a Heroic Spirit is a spiritual being that has both form and power derived from accumultated ideation of Humanity, different from Fairies that exist as power in the world, but assume a form woven by ideation. So, though I really hate that specific aspect being taken as canon, being a joke isn't really a problem. Heracles and Medusa are said to be 100% being derivations of legends. As the true name of Ghost Liner says, ''Bounded Record Belt'', they are the record of a phenomena as a finished thing, that is, they aren't living things, they should be taken almost as data manifest.
''But how is a phenomena that didn't take place recorded in the first place?'' stands as an obvious question. To this - Reality Marbles existence, Malignant Information, Souls (aka the things that stores memories ''eternally'') are basically described as OP HDs impossible to believe in + the Soul recording memories, therefore not necessarily ''true, existent living things/objects'', but also phantasia, or even Reality Marble themselves if those are there,
Anti-Fortress is basically saying it is a rank in destructive power above Anti-Unit and Anti-Army (which have the ''same rank of destructive power'' and are different in so far as Anti-Unit ''affects one target'' and Anti-Army has the capacity to affect a number of targets over an area. The use of ''Fortress'' is, given context (and given the use of the same concept, ''Fortress wall'', in Rho Aias - each petal = one fortress wall) symbolic to represent the increase of destructive power.
Anti-World =/= Anti-Planet. Anti-World are NPs that deal with the manifestation of the living being of the planet that covers the true surface of the planet - World Interference is say to be something like the powers based on interfering in probability, the laws that control phenomena, Marble Phantasm. To simplify, it affects the Texture, not the planet. The thing called World in Nasuverse isn't the planet (the celestial body). When he wants to refer to the planet, he uses ''wakusei/sei'', which he has done like... single digit times?
Anyway, that's why Elementary, My Dear can alter reality and make things ''Elucidate-able'' and why Ea is basically a space-time ripping sword-wand thingy. There's also a ''Anti-Star'', which is actually ''Anti-Celestial Body''. It includes things like Edin Shugra Quasar, Per Aspera Ad Astra and Pale Blue Dot. Even them wouldn't have true planet busting power under normal conditions, or at least that's what Da Vinci tell us, cause Counter Force.