Okay, this time I did it on Emperor (with the right city placement in Nubia) and even though all victory conditions are checked the game doesn't seem to recognize that I won. I've attached the save, just hit next turn.
Barbs and the AI are ridiculous on this difficulty, I could only do this by getting city raider 3 from the Jericho town defenders and then capturing the Sumerian capital. This required a significant amount of luck (and S/L). Maintenance costs are also way too high, I was completely broke after taking the 2 cities in the Levant + Ur so I kept wasting my hammers on building and disbanding units. My strategy also involved abusing the Stonehenge for the first UHV and the fact that for some reason Egypt skips anarchy, which I assume is a bug.
So Emperor is too hard, Monarch is too easy and I don't even want to try Demigod - I'm assuming the first stack of barbarian city defenders would destroy me

This doesn't apply to all civs though. I was able to capture the Levant and Lower Egypt with the Hittites on Emperor, and could've gone further if I hadn't collapsed. AI tech speed was still terrifying, apparently Egypt survived the barbs by building Hadrian's Wall and they had more than 1200 score before they finally collapsed. As a comparison, I was second in score with ~350 points.
Maybe unit costs could be increased, in my Hittite game Hattusa was producing one 10 xp huluganni per turn at the time of the Egyptian Empire, later 15 xp horse archers. And although it's not a big issue on Monarch (well except when playing as the Huns), AI unit spam on Emperor is a bit problematic.
Also, I'll admit that I haven't tried most of the civs on this version yet, I'll try to give more feedback when I do.
PS: thanks for the great mod, I've had a lot of fun playing.