What exactly makes you think that "shadow" suddenly indicates actual R>F in the cave allegory? Analogies alone aren't enough proof for R>F, there needs to be further context showing that the higher level is literally more real than the lower level. And while "shadow" being used one way in a different context doesn't necessarily indicate its usage in every context, the fact that "shadow" is consistently used in a non-R>F context does at the very least imply that it isn't being used in an R>F context in the cave allegory.
Because the shadows in the cave analogy are specifically referring to Plato's theory of forms. And if you want further proof, there's the Tree being the origin of everything, including laws and truth. Since ontologies are a thing in HI3, then the tree by extension must be thus also be the origin of all possible ontologies. Furthermore, the tree is said to treat the worlds within it as if it were data in a server, which heavily suggests R>F. As for the term 'shadow' not being used in the R>F way. I'll just put it bluntly. What else could 'shadow' mean while being used in the context of Plato's cave. In the other cases, the shadows had other possible meanings that wouldn't contradict with the Plato's cave analogy. However, there is no other possible context for 'shadow' in plato's cave analogy, unless you want to argue that they are talking about a literal cave with literal chained prisoners and a literal flame.
Also, the analogy still isn't consistent. Unless this is another weird aspect of the translation, Mobius says that the shadows on the cave
are the world to them even though the world, including Earth, is full of Honkai. OP pointed out the fact that the Honkai is in fact a form of Imaginary, so scaling Imaginary as having R>F over the "shadows" would require scaling Imaginary above itself. That is nonsensical.
The world is filled with Honkai, yes. But Honkai is never EVER referred to as being from their world or being on the same level as their world. In the earlier chapters, it is thought to originate from the tree, and from the Cocoon in later chapters. The Imaginary and Real space is also suggested to have an R>F relation. The 'real space' is a unique case in the infinite amounts of 'Imaginary spaces', but is also the only space that can produce 'meaning'. Everything that exists in the Imaginary Space, unless given appropriate 'abstraction' or 'projection', will be meaningless to humans.
Aka. The Imaginary space includes everything that could possibly be, but our senses can't comprehend that. Real space is the things that we can actually comprehend. This lines up quite nicely with Plato's analogy of forms.
There is also no consistent way to frame what each part of the analogy even represents. If Imaginary is all that is true outside of the cave, who are the observers? The observers clearly aren't humans because they're the shadows. Mobius talks as if she and Kevin are observers, but that makes no sense either. They're still humans, so they would be shadows. You could argue that them having Stigmata and power over Honkai is what makes them more than just shadows, but that makes no sense either. Did the shadows jump outside of the cave to the Stigmata, become real, and then go back into the cave to be observers chained up inside of it? The allegory only makes sense if the observers were always chained up, not shadows who became observers. Who even are the shadows? Are they the world, or the humans? So much of this analogy just goes unexplained.
The answer is simple. The observers (I'm guessing you mean the prisoners) are completely irrelevant when only talking about what's 'real' and what isn't. The fire is the 'form of the good', the objects casting the shadows are 'forms', and the shadows are 'particulars'. There is no need for the prisoners. The reason Plato added it was to show how people will reject ideas that conflict with their world view. In fact, that was the main point of the entire 'theory of forms'. The observers were never given a discrete ranking in the analogy of 'forms'. The 'contradictory' statements were also given by two people under two very different contexts.
Mobius wanted to ask Kevin what he would do if he gained the ability to go to 'the true world', and WoS is telling us the relationship/difference between the humanity and the Stigma space.
Additionally, the fact that Honkai is a form of Imaginary would force us to conclude that Honkai altogether has R>F over basline reality (
since all quantitative divisions of a 1-A power must also be 1-A), which is just ridiculous. White Comet Kiana uses Honkai and would thus have to scale to 1-A. Even the OP seems to realize that scaling anything less than the Authorities of the Cocoon and Otto Apocalypse would be ridiculous, but fails to account for the fact that scaling Imaginary to 1-A would force you to scale literally all Honkai to 1-A as well.
Yeah, it forces the entire hoyoverse cosmology to 1-A. I don't see anything wrong with that.
Jokes aside, the Honkai isn't a magic power source that makes everyone that contact it a god.
1. While it is an energy source, even a small dosage of it can be lethal. And even for beings with incredibly high honkai resistance, Honkai overdoes is still possible. Even for herrschers, the amount of honkai that they can hold in their body is finite.
2. Only herrscher cores have the ability to utilize Honkai to its full potential. Without it, honkai energy is basically just a stat amp. Aka, only those with access to herrscher cores can qualify for 1-A via Honkai energy.
For scaling, this would mean that only the top tiers of the verse (herrschers, MOTHs, Otto) would scale to this tier. And while, yes, that is nearly everyone, it's not all of their versions, especially the earlier battlesuits. In fact, it averages out to less than one 1-A level battlesuit per character. (Excluding Kiana for having like 5 herrscher forms, and Durandal for having the abyss flower in basically every battlesuit).
And I already see the "1-A beings can't be defeated by lower tiers" argument coming. This can be dealt with by remembering that the herrschers don't have an infinite energy pool to draw from. Herrscher authorities uses Honkai energy, and since the amount of honkai within a herrscher is finite, the first few herrschers could be dealt with simply by stalling them out until they run out of energy. And then once the divine keys are made, they would be of equal tiers anyway.
And no, this isn't an anti-feat for 1-A because they are either being defeated while not having a 1-A tier of power, or they are being defeated by a 1-A tier.