Mknote did this by modifying the original system files rather than creating brand new systems. This is also why he needed to move the places around because he created a new map and the geographic locations were different on there for all of the new houses (one of the new ones he made was called "Hispania".
Everyone needs to please stop saying how much easier it is to edit the resources files - this has nothing to do with that. This is meant to augment that and make it easier and more flexible to do things with your mod.
Also, I should point out this mod does tell you how to move the names on the map and remove them entirely which to my knowledge has not been done before.