I don't see how "calibrating to resemble a human's vision" is going to help you here. What this does is to prove what RE'ers such as myself have been saying all along - you can't get a sunset/sunrise to happen with a Flat Earth model without messing up the location of the sun in the sky for other places in the world.
You need rules of physics that allow light rays to bend in order to explain how you could get sunsets to happen...and I'm quite certain that your 3D rendering software doesn't support that. (Oh - you're using Unity3D - so I can tell you right now that it can't do that).
As it happens, my day job is as a 3D graphics engineer and I modestly submit that after 40 years in the business, I'm a world leading expert on the subject - so you're not going to be able to pull the wool over my eyes here!
Your simulation also has two very serious flaws - even by FET standards.
FIRSTLY: The light cast by the FET sun can't be omnidirectional (like a 3D graphics omni-directional light object) - and it can't be a circular cross-section light source like a flashlight either (as the Wiki claims) because it has to be able to illuminate a semi-circular portion of the Earths surface in order to explain how there can be a sunrise at a point 180 degrees of longitude away from other places that are seeing a sunset:
In the image above, the sun is over the equator and it's noon in Australia and noon at the North and South poles. Notice how a semicircle of the flat earth MUST be illuminated in order to explain what we see in the real world.
So - first amend your model to get the right light source shape - and then explain what the heck you mean by "calibrating to resemble a human's vision" - bearing in mind that I'm an expert and I'm definitely going to call you out if you attempt any hand-wavey flim-flam.
I speak your language - so please tell me how you'd alter (for example) the projection matrix values (or whatever else it takes) to get your "human vision calibration" right.
SECONDLY: I can tell you before you start though that to accurately portray what the FE'ers are claiming, you're going to do a LOT more clever rendering work than this. In their world, light doesn't travel in straight lines...or else there can be no sunsets over level ground/ocean - they claim (vaguely) that the rules of perspective are "wrong" and that maybe light gets refracted somehow to create sunsets. Sadly, neither of these can be simulated in Unity - so your pretty simulation is worthless.
Getting any 3D rendering package to simulate curved light beams is HARD...and without that, I'm afraid your pretty pictures only demonstrate very clearly that FET is incorrect.
If you have the ability to do 3D graphics with curved light beams then I'd be VERY interested to see the results - but I somehow doubt you know how to do that.