CFYOW
Out of curiosity, what was the debunk to this? Outside of "them being planets doesn't inherently contradict the sentence/it's just a comparison".
現世と尸魂界を星と喩えるならば、その星同士を結ぶパイプラインが「断界」であり、それら全てを取り巻く宇宙空間にあたるものが「黒腔」と呼ばれている。
"If the world of the living and the Soul Society could be likened to planets and the pipeline that connected them were Dangai, the void of space that surrounded those was called Garganta." ~VIZ
"If, to speak figuratively, the world of the living and the Soul Society were planets, the pipeline linking the fellow planets would be Dangai, and the outerspace surrounding everything is called Garganta." ~Me
喩える means: to compare (something) to; to liken; to speak figuratively; to use a simile; to use a metaphor.
Here is a list of example sentences using the kanji as well. The example sentences, at least to me, seem like the kanji is exclusively used to compare objects that aren't the same (aka comparing a planet to a planet). Rather they compare raisins on bread to electrons, or walking into a scary scenario to entering a blackhole, etc.
My reason in pointing that out, is that this kanji seems to be used primarily metaphorically/non-literally. Furthermore, VIZ translated
宇宙空間 to "void of space" rather than "outerspace", which may seem nitpicky. However, if you went by "void of space" you could claim that the comparison is literal, because Garganta is a void of [reishi] space, but Garganta is certainly not outerspace. Considering the actual kanji used is for outerspace as opposed to just a void of space, I am further questioning the intent with the comparison being able to be taken literally.
Going by the sentence, if the realms in question were literally planets, Garganta must also be literally outerspace. Furthermore, the fact that Garganta isn't literally outerspace, seems to imply that the sentence and comparisons in it are purely metaphorical. My line of reasoning being, if the realms were planets why mention "if they could be likened to planets" why not just call them planets? For example, if the realms were straight up planets I'd expect the sentences to go more akin to: "Considering the living world and Soul Society are planets connected by Dangai, Garganta is like another outerspace surrounding them all."
I'm aware this is majorly semantics, so I'm content if the majority just vote to throw away this statement more or less. However, to me the point of easy to understand comparisons (as this is being argued to be nothing more than) is that they take things that are hard to understand and liken them to things they are not but are much easier to understand. Prime example, if someone were to ask me how important my mom is, I could (to steal from Bleach) liken my siblings, dad, and I to planets, where my mom is the Sun we revolve around; I could also liken my family to a single living being and my mom to the heart that keeps the being alive. Point in case, I can't think of any comparisons used to "dumb things down/explain them" that compare whatever is being talked about to itself.
Lastly, to reiterate what I said earlier, if the realms were just planets, but they needed to make an analogy for Garganta, they could've just called the realms planets and said the Garganta was like a "second/other" outerspace. Personally, I feel said statement from CFYOW carries some "realms aren't planets" intent within it.
Toshiro
To touch upon Toshiro's planet statement, I'll quote my last CRT, but tldr it doesn't inherently mean the realms are planets, the Kyogoku could just be connecting the realms at the point where those planets are.
That is not inherently the case, just because the Kyogoku is connecting the realms at two specific places (two planets), does not make the realms inherently planets. For example, if I grab someone by the hand and drag them around, I am pulling their entire being while only being connected at the hand, but if someone points out that two hands are connecting that doesn’t mean we are both only hands. Essentially, all Toshiro’s statement means is that the Kyogoku is connected to two planets, it does not prove in any way that the Kyogoku is only dragging planets.
Universe
VIZ does throw around the terms "universe" and "all of creation" a decent amount of times throughout the manga and novels. Those scans have been thrown around a lot in this thread, so I won't bother finding them and linking them for my own sanity. However, I'll bring up that throughout every single mention of "universe/existence/all of creation/etc" it's in reference to the sum of the realms and perhaps the other dimensions (like Garganta and Dangai). So, I believe destroying all the significant realms (3 realms of existence, Dangai, and Garganta) is still universal, regardless of how we treat the sizes of the 3 realms of existence (HM, SS, and WotL). The reason I bring this up (because it's lowkey irrelevant to the thread at hand), is because I think the realms being a major piece of the universe again implies they are supposed to be larger than planets, and the implication potentially goes as far as to say WotL + SS = a universe. [If scans are really, really wanted for this I'll snag them]
Miscellaneous
Other than the above two instances, "planet" and the realms are never referenced in the same sentence. Every other instance of the realms (primarily SS and WotL) being mentioned doesn't concretely distinguish between what they are. There exists moisture and water outside of the planet Earth, so not even the infamous Yama Bankai statements inherently refer to Soul Society as a planet. I could go into ever other instance and mention why it isn't inherently referring to a planet or larger realm space, but I find that unnecessary as they don't aid us in determining what the realm actually is. Personally, as for determining what the realms are, I find most everything besides the cosmological descriptions and mention of the word "planet" to be fluff that doesn't narrow things down.
Conclusion
As for how we treat Senna's feat and addressing that directly, the cosmology depiction in the movie is slightly off from Kubo's final diagram. Dangai in the film highkey takes the shape and role as Garganta in the movie (considering the movie was conceived prior to Garganta that is probably why). In all Kubo's later depictions of the cosmology, Dangai is just that tunnel structure we see and Garganta is the massive reishi void surrounding everything, but in the movie Dangai is both. So, I could see an argument for treating the MoN cosmology (for the sake of calcs and feats) as different from the end of series/more fleshed out cosmology.
In other words, I'm okay with treating the realms as planets for Senna's feat, due to the visible differences in how the movie portrays the cosmology vs the TYBW/CFYOW descriptions (which to my knowledge is what this CRT is addressing). The matter of if the realms are always and only planets should get its own spotlight.
