Perhaps more civil wars would be nice... I kind of loved to hate them. I was constantly thinking of them if I got a bad king, and as the HRE I got plenty of those. Then Civil Wars were just around the corner, but sadly they tended to come when another faction had decided to give it all to crush me.

Anyway, my point is that I believe the Spanish could still have won in the end even with no civil wars. Prior to them they were slowly taking back land and suffering few strategic reverses (but they did suffer tactical reverses often enough). So inherently it seems the Spanish were just a bit stronger, that woud in my mind equate fair enough to the Moors being slightly behind in technology, but not stagnant as in MTW.

So the Spanish get Chivalric Knights? Moors get a units that is somewhat weaker but stronger than their earlier units. The Spanish get CMAA? The Moors get an upgraded AUM.
This doesn't need to be fitted to M2TW directly but the system should work.