My browser crashed as I was about to send the whole analysis, it was so long and detailed... ;_;
I assume it to not be a pasta

I reread it very many times and tried to understand it as good as I can

1. Unconscious association of a certain type of pony image with peace of unknown origin. Probably neural wiring misfire. Since you describe more things associated in chain with it then it probably was just the initial domino.

2. Entering a trance of ponies related to peace and purity. Interesting. I never had it this deep, I had my brain melt in innocence and joy for a few seconds at most. Did you feel something weird like unreal taste in your mouth or in general taste sensation of any sort? Did you feel something at all comparable to migriane like imaginary sparks? Static noise on an imaginary level? Skull compression? Would you say that if you closed your eyes and focused then your "center" moved to the place where your frontal lobe is? Would you say that the point of vision moved to above your forehead while the vision had that sharp static or something since eyes were closed? Were there distinguishable sparks among the static? Seems like a neurological issue.

3. Dreams of an abstract object. Did you feel as if peace emanated from it? What was the background vision like? Did it have real colors or were there imaginary spark-like colors of varying intensity? Was the background moving? How high above ground of that point of view were you? Ground or how high above it? Was there a border over what should be the sky? Was it of hallucinatory nature strictly? It seems like it.

4. Expanded perception with a new axis. Probably related to every other symptom and some neurological damage or temporary disfunction and dependent on whatever it the original cause of that chain of experiences.

5. Voices of peace perhaps? When I was very little kid mine were boring. Whenever I went to the bathroom to wash my hands in front of the mirror I would look into it and suddenly a voice of some sort would proclaim a short sentence or a word of language that did not exist but I could sense what emotion it carried and what in general it meant. The voice or voices would be very clear and had no acoustics or source as if they were a played sound effect with my headset on but they were clearer than real voices. There were also tiny shadow people that would be the sources of them and whenever I wanted to look at one through the reflection they would disappear as soon as I moved my eye and would get irritated but they never threatened me hard. So to cheat the system I would kneel before the mirror while washing my hands to be below the sight of reflection and would face the ground and I think I know exactly what you mean with the voices! Hallucinations! When I was little now that I look at it I was quite schizophrenic and later paranoid. Paranoia persisted to an extent but voices and visions went away! Voices are too much for it to be a coincidence.

6. Strong smell indicates neurological damage probably. I once smelled something at age 3 and it triggered some tingling in my brain and amplified the smell almost infinitely. It was also related to dreaming because I could smell it 2 more times in dreams and after that I never smelled it again. It was an imaginary of almost infinite intensity but not pronounced at all. I also would say that what I described in point 2 is what it was associated in my perception of it. The gravity sensation also altered during smelling it as if I were underwater and upside down but there was no water.

7. The dream state of perception remained after waking up. I had this once and I could not distinguish reality from imagination for a bit and then I had a realization that whatever happened in my imagination during sleep is not real and I had to function for a week until I went back to normal but it had no particular visuals or anything, just as if I woke up from another reality and had to relearn things. I doubt how comparable it is. Interesting experience.

8. The smell. I had also some triggers of that smell but they only reminded me of that extremely intense experience and not repeated it.

You either are
1. Developing a hallucinatory illness like schizophrenia or
2. You had a brain clot or related issue and it for some reason passed without severe damage
3. An extremely unlikely chain of neurological errors consecutively, but probably some damage played into it

Were you like 30-40 when it happened perhaps? Are you sure you are not prone to stroke? Are you drinking too much taurine daily for a few years perhaps?