*sigh* Like I said, that particular title "The Jewish Empire" is purely CK2+. But the fact that rulers are converting to Judaism isn't from CK2+. It could just as easily have happened to Karl after he forms the Holy Roman Empire, then you'd have a Jewish HRE.
That makes a huge difference then. The forming of a stable empire is a huge power shift. This doesn't happen in regular CK 2 play, hardly ever does a different religion rise up, convert all the provinces around them and form a new, stable empire.
So i'll ask again. Has this happened to anyone. Has anyone, ever, seen a large jewish empire outside of a modded game. If so did it last longer than 5 years.
When one person or more says yes, then we can look at how likely this is. Does it happen one in every 10 thousand games of CK2, and when it happens how long does he last? If so, and if not long, then there is no issue at all.