OP: You need modify EDU and scripts and descr_strat, remove all "hinterland_" text, i.e. rename building "hinterland_farms" to "farms"

Since a building name may be referenced in many places, it'd be better if you get some search+replace tool to scan all *.txt in EB directory, and backup everything you modify. It's not a simple task unless you're a modder


PS: walls and core buildings cannot be destroyed, and destroying roads doesn't downgrade the real roads on campaign map.