Temples aren't zones, they're locations. Different considerations, there. It's not like the value calculations being different is unknown, here, it seems display cases work for locations but not zones.
Good point. Any idea how the calculation differ? Also is there any way to see the exact zone value? (all the testing I seen here used the location value to infer how engraving affect zones)
The testing I've done suggests that it's just that locations don't suffer from overlap depreciation. So for zones that don't overlap the location value *should* be correct. The only outliers where we can't determine value precisely is with overlapping zones. Basically, unless your zones are overlapping to such a degree that both zones cover the engraved side of a wall, it's not even going to be relevant.
You could probably get rough estimates based on
room zone quality descriptors from assigned rooms, i.e. set up your testing zones and assign them as personal rooms, then check the room quality names. Honestly this feels like one of those things where you don't really need to know exact numbers to understand optimal setup -- double-wide walls, don't overlap zones where value matters, done. For the most part even if locations can double-dip on value it feels better to keep them split up, both for aesthetics and to reduce crowding.