I would like to be able to enable sanity loss only when below y = 0 in the overworld. This means the sanity indicator shows up and all, but unless the condition is satisfied, the player cannot lose sanity.

The closest thing currently seems to be the multiplier fields, but they apply everywhere.

In general, it would be nice if we could specify something like ["dimension1;yLevel1", "dimension2;ylevel2", ...] such that (active/passive) sanity loss is only allowed happen in each dimensionN below its corresponding yLevelN.

This would allow disabling sanity loss in certain dimensions or (as in my case) creating "hardcore" areas where the player has to worry about their sanity draining, while still allowing players to replenish their sanity outside those areas.