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"
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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.