Learn moar astronomy. The Round Earth model does not predict that the sun rises exactly from the east on equinox for everywhere on earth, only from points along the equator.
This is not correct, Tom. The celestial equator (CE) intersects the geometric horizon at points due east and due west of an observer anywhere on the surface of the spherical earth except at the poles (but at the poles, the CE
is the geometric horizon, and east and west have no meaning). At the moment of the equinox, the center of the sun is on the CE (that's what defines an equinox), therefore, geometrically, the center of the sun rises due east and sets due west for an observer on the surface of the spherical earth at the moment of an equinox (except at the poles).
If sunrise or sunset at your location is
not at the exact moment of the equinox, the center of the sun will be a little north or south of the CE at sunrise or sunset. Is that what you're questioning? That's going to be the case whether you're on the equator or not. It's irrelevant, anyway. If you're working at that level of detail, then your point is moot because the sun isn't rising or setting at the equinox everywhere on earth, only at two particular longitudes.
You will get some additional slop because the CE intersects the horizon at an angle if you're not on the equator, and atmospheric refraction causes the sun to appear above the horizon when it's actually just below it geometrically, but that is not very significant in low and mid latitudes unless you're taking very precise measurements; if you are taking precise measurements close to the horizon, you need to account for refraction anyway. At high latitudes this will become very significant.
The slightly non-spherical shape of the real earth and presence of the atmosphere add complications, but the spherical-earth model itself predicts exactly that.
We have never seen any sort of documented observation of this eastwards rising sun phenomenon from the equator.
Apparently you haven't looked.
Furthermore, the length of day varies to be more or less than 12 hours throughout the year. There are two days when the length of day reaches about 12 hours. It is of no surprise that there are a couple of days which reflect these values and which historically represent the changing of the seasons that are defined by the length of the days.
While this 12 hour day is logically reasonable, we have not seen evidence that it holds for all points on earth worldwide.
It doesn't. At (or even very close to) the poles, the sun will slowly emerge above or settle below the horizon over a period of a few dozen hours, and stay above or below the horizon for months at a time. It takes about 36 hours for the center of the sun to move from 1/4 degree on one side of the CE to 1/4 degree on the other. Since the apparent diameter of the sun is about 1/2 degree, it takes that long for the entire sun to cross the CE, and, similarly, to completely emerge above or disappear below the geometric horizon at a pole.
This "equinox proof" is completely hypothetical. Every year it comes up, and every year you guys fail to provide evidence for your premise, and continue to make baseless claims without evidence.
You could easily check for yourself, you know. Since you deny that it happens, you must either be refusing to, or are confused about what direction is due east or due west.
Lets make it clear: If you have no evidence, there is no reason to amuse your claims at all.
Based on the last ten years, here is what will follow in this thread: We will see further claims and appeals to authority and incredulity, but we will see no actual evidence in any form.
You've been making this appeal to incredulity for ten years and never even once tried to see if it's true? Wow! You've had 40 opportunities to do so in that length of time!