"Total War Attila: The Long Night" Question

Relatively recently I heard of an overhaul mod for Attila called "The Long Night." I was immediately attracted to it, because the premise seems to be "Hey you know how Attila is already hard due to climate change, a horde of invading armies, and crumbling infrastructure? Well what if it was that, but even more?" The map is locked into an eternal winter, plagues seem more common, all the civilizations of the world are being brought to their knees. But then there's the biggest thing. The mod promises:

"Demonic Invasion: Starting in 666 AD, a Demonic invasion will occur, with the forces of the Undergod invading Europe from the northeast. Precipitating this will be multiple events and a great plague, signs that the end times near."

Frankly, this all sounds like peak fiction. Except there's one problem: the friend who introduced me to it played it and there was no demonic invasion. She searched the entire map and could not find any demonic armies, no Undergod, nothing. And the few results I find online about this mod indicate this has happened more than once. So my question is, if you have played this, have you ever encountered the Undergod in this game?

[Link to the mod here](https://steamcommunity.com/sharedfiles/filedetails/?id=3385475658&searchtext=)