Shouldn't LIQUID just be MATERIAL?
The interaction page on the wiki makes no mention of it, at least.
I can't think of any problems with the NOFEAR effect. Are you attempting to make zombies with the interaction? It targets corpses, but doesn't raise them.
I have no way of telling if LIQUID or MATERIAL works. The errorlog doesn't give me any lip about using either, and trying to track down an affected region is next to impossible.
That interaction is meant to target anything, the corpse target bit is a leftover because I wrote it over a copy of the example interaction. I would have added FLEEQUICK along with NOFEAR if it was a supported tag, because I'm trying to simulate that it's raining molten rock and nobody wants to stick around for it. As it is now, it only makes the region so terrifying EVEN THE DEAD FEAR IT. Impressive, but useless.
That will only do anything if you have an inorganic material named WATER - if you don't, it'll probably glitch out and rain magma (or nothing at all). Also, it will still count as "freakish weather" and disturb your dwarves, so you probably don't want to actually use it.
I've used INORGANIC:WATER before in projectile attacks, and te names used for its various states sound right(water, ice, etc.). I used it the same way in an adventure mode reaction to give myself drinking material as well. It never gave me any trouble and I've assumed the whole time I found the code for water.
I used water for the weather effect because I thought it would act as a vector for the interaction's effect at first. Can't explain the logic behind that but I got the idea that wasn't the case after awhile. Now it's just there because I never took it out. It's sort of useful when it appears in regions that don't normally get rainfall, and if anything it's an indicator that the regional effect is about to kick in.