also sorry for the 2nd mention lmao, but he clearly intended to at least mess up the timeline, having complete control over it, kinda like zamazu from DBS. Edit;
He also says it in the context of the TRUE RESET, which further solidifies that he refers to the timeline. thats all from me, save us OP
No no, we're good. Let me oversimplify and get my thoughts back in order.
What I meant to say is all the 5D arguments are basically trying to say that Asriel's Reality Warping clearly erased all the timelines.
I have an issue with this, because afaik, Toby is very explicit in showing what is actually destroyed. CHARA did it, but not Asriel. To me, it's clear that other timelines still existed in the Omega Flowey fight, what he does specifically is more like bring us to a personal pocket dimension and removing/blocking our access to a different save file. It's not like the file no longer exists, we still go back after all.
Even them, Chara's deletion of the files feat isn't used for Monika to get her to L1C.
I'm not gonna argue for the immeasurable speed stuff anymore, especially since Toby himself already admitted that some of the translations don't make sense but he wanted them in anyways... for what is practically the "lulz"
We already know the localization isn't perfect and can very easily be misinterpretated or not have the intended OG meaning because of a variety of wacky decisions (e.g. the "smells like sushi" line meaning something very different, aka vinegared rice, yet Toby insisted on keeping it because "he thought it was the line was famous" despite it making NO sense in Undyne's context since there should be no rice involved in that scene iirc). This was stated in the blogs you provided outright.
Regardless, I personally just don't think Undertale has any L1C scaling. It's not like Chara can pop out of the screen and then straight up write on it like it's fictional, aka Quantitative R>F, and again, there's no extra dimensional axis for 5D to be considered imo. Using the "save file is 5D" arg feels silly when Undertale is known for doing 4th wall breaks... similar to Monika. We don't have Monika at L1C just because she can delete the files of other entities in the game.
The issue is the characters ARE diegetic, I'm not disagreeing with that at all. The problem is because they're in the game, they are limited
by the game and whatever keeps it afloat... like the save files.
SAVE files being broken feels more like blocking access rather than straight up annihilating the timeline outright. As I said earlier, nothing says that that timeline is destroyed. We literally go back to it like nothing happened. It's likely a Rupert's Droplet situation where deleting certain weak points can cause a massive chain reaction but actually directly destroying it requires far more complicated and potentially even unreachable levels of power.
SAVE files are more akin to the world itself, the data, rather than being completely separated from it just because it can retain data that Asriel/Chara "destroyed". It
is the world, THAT is why it's able to retain data. It isn't superior to the world in any 5D capacity, it IS the world, and hence it causes massive chain reactions when edited. The destruction of timelines is, really, more like chopping off branches off a tree. The tree still exists, it has to to be interacted with in the verse. And Chara, despite destroying "everything", leaves the foundation of that tree to let us still interact with it, because destroying it entirely would also destroy Chara. They can't be separated properly like what a 5D entity would be to the cosmology, and as I've already said, the cosmology doesn't feel 5D. It can't really be 5D when they're significantly affected by things that haven't been shown to be beyond 4D outside of taking some weird interpretations with how information manipulation is utilized.
Again, we don't have Monika L1C, we just have her with Information Manipulation since that's what she can edit, and hence she's L2C. This should also apply to Undertale.
TL;DR: This is more akin to a 4D object self-imploding because of a glaring weak point (save files and information manip) rather than 5D entities destroying it.