Oh yeah I forgot to mention these, of course the mongols did get a little workover since the beginning, namely in Horse Lords. A good one by that, in my opinion, specially now that the game has been developed far further: Even without the specified mongol-invasion-event it just so tends to happen at least once every hundred years, that some strong horde evolves, eventually to the point where it raids up into the balkan and western europe.
That said, same as the mongols Egypt's Mamlukes were some sort of "end boss" by game design, being harder to handle than anything else around, when we did not have to worry about other stuff such as vassal limits, threat or a discontent council. The same counts for the Varangian Guard, with the difference of them being already comparably nerfed (if the comparison is taken with mamluks/ghilman).
The simple reason for this is, ERE was playable since the very beginning, hence why it did not get that op a merc stack.
I personally don't mind they left them in with SoI. But when you observe a revolt in early game egypt and in early game Byzantine Empire, you'll see the difference in power- the Emperor will just be screwed against larger factions, while the Sultan of Egypt, even with everyone and their cousins in revolt, will smash them right away by sending out the Mamluks.
