If you don't understand the underlying file, don't bother editing it either by hand or with an editor. The core_building tree is very tricky and most of it cannot be modded at all, and what can be modded will likely break RS because of how the mod relies on various AoR to do things.
So I repeat, unless you are an EDB expert, and you aren't, don't play with the EDB from this mod as there are 1 million different ways you can break RS by playing with the file and almost every single one of them would be a reasonable change in any other mod.
If you want to learn some about the EDB file, go to
forums.totalwar.org/vb go the the scriptorium for the Rome series of games and dig around until you find the complete EDB guide, and above all learn the hardcoded limits of any file you are going to change. This information may also be available in the wiki on this site.
For future reference all modding questsions should be posted in the modding forum (not any RS related forum) as this is not the appropriate place for it.