Your point still doesn't cover issues. Also. I have a new few points which actually do support my argument I just came across
You're generalising too much. While it's a cartoon, the Simpsons aren't nearly as toon force based as most other cartoons, to the point where it's mainly a greatly exaggerated reality rather than an unbased fictional world.
They are pretty toon like. Even in regen it's consistent. Moe has had his head crushed flat. Homer had part of his head cut off. His heart ripped out. Bones in his back broken. Then their other consistent gags like teleportation, Resurrection, Non physical interaction. It's in no way unreal for Homer to have this.
We know that the gap wasn't completely filled up because there was water still in the gap, with most of it still being in there.
That's not how those kinds of cogs work. As well. The water is shown to be leaking out. Once it started to come down, water was drawn to leak out on all the side. I have a picture to further proof my point. But it's ahead, So I'll wait one this.
We also know that Homer causes a jam in the very next part of the scene, even if it's temporary, so we know that the force of one cog wouldn't be enough to completely flatten Homer
Unrelated. He jams those up with his body. But the early scene he doesn't cause any remote jam in the cog.
The cracking sounds don't support anything more than Low-Mid; if I'm honest, that's one of the only reasons why I don't think the feat should be discarded entirely.
It was where his brain was. The cog itself was both large enough to fill most of not all the gap, and cogs like this are supposed to fill most of the hole, this breaking would both cause head and likely beck breaking due to the fact of how his head was inside.
Plus. Should bring this up. His entire body got crushed as well. His head didn't just go under it. Here's a good frame to support my case
This frame here shows most certainly that his head was being crushed inside. We even see water leaking out as well. And this is when his head was coming out. Meaning that his head when under the cog was flattened even more. And this frame alone should justify mid regen. That's serious brain damage right there. Half his skull is crushed in. Which is all it takes for mid regen. Even crushed halfway would be considerable mid regen. Considering it's major brain damage. And he healed so quickly. So what we see here alone should help justify that, and his head being under it entirely meaning his head was even more crushed (even if we assumed not the very bottom).
On top of that. Look at the body. His body has been almost entirely flattened. So a massive amount of his organs and his heart would be flattened nearly entirely. Not to mention. The cog itself definitely would have broken homers spine. Wether it was under the flat part or crushed into a hole. It would have broken and flattened his spine. So several important and major organs and body parts like the heart and spine would have been flattened with the rest of his body and he healed. This adding on even more to support mid.
So he both healed a flattened brain, Broken and flattened spine, and flattened body and legs. This should qualify for Mid regen. Which I should note. This regen isn't even new to the Simpsons. Some characters like Moe have had their skulls crushed flat before and healed very quickly.