I haven't checked in detail, looks like you've got right idea, you need to check descr_strat for all instances of hinterland_unique2... and simpler way to fix your problem might be to just to comment out or remove the religious_belief line

if you definitely want to destroy the building search the EB script (in data/scripts/show_me)
for any reference to muro_pianto in case that building is needed for something in the running of the script