Trouble doing all civs playable

[Ibn-Khaldun]

Roman rebel factions don't work because they need some provinces at the start of the game. Without it the game will crash. Also, it would be wise not to let them stay as shadow faction because this also could cause CTD's.

Romano-British also need a province just like WRE/ERE rebels.

Slavs and Ostrogoths are emergent faction and they need some armies do be present at the start of the game.

EDIT: Another thing..

marian_reforms_disabled
rebelling_characters_active
gladiator_uprising_disabled
night_battles_enabled
brigand_spawn_value 10
pirate_spawn_value 12

Unless you like fighting against brigands/pirates you might want to chance those numbers to 100 and 120. Big number - less brigands/pirates; Small number - more brigands/pirates