So i just downloaded and played SoI, and to be honest i hated that mod so much i deleted after 30 minutes of playing it. But there's one thing about SoI that caught my attention, and that titles. So even though i believe some people have already suggested this, im gonna suggest this be modded in, shouldnt be too hard i hope? 
1) Controller of the Holy Land:
-Must be a Catholic nation
-Must control Jerusalem
-+5 stability
2) Holy Roman Emperor:
-Must control at least 10 cities (vassal counts)
-Must be a catholic nation
-Must be the civ with most Catholic faith points
-Your civ name gets changed to 'Holy Roman Empire'
-+5 stability
3) Ruler of the Latin Empire
-Must be a catholic nation
-Must be in control on Constantinople (vassal doesnt count)
-+5 stability
4) Sultanate of Rum
-Must be a Muslim nation
-Must have Constantinople as your capital
-Must control at least 10 other cities
-+5 stability and +5 faith points
just a suggestion

1) Controller of the Holy Land:
-Must be a Catholic nation
-Must control Jerusalem
-+5 stability
2) Holy Roman Emperor:
-Must control at least 10 cities (vassal counts)
-Must be a catholic nation
-Must be the civ with most Catholic faith points
-Your civ name gets changed to 'Holy Roman Empire'

-+5 stability
3) Ruler of the Latin Empire
-Must be a catholic nation
-Must be in control on Constantinople (vassal doesnt count)
-+5 stability
4) Sultanate of Rum
-Must be a Muslim nation
-Must have Constantinople as your capital
-Must control at least 10 other cities
-+5 stability and +5 faith points
just a suggestion