About 4 days ago I posted an issue regarding possibly modifying the villager AI for the weather siren and you liked the idea. However, I found a cross mod issue you may want to look at while implementing that.

I play Minecraft with Minecraft Comes Alive, so I was pleased to see that MCA villagers will still run inside when a severe storm approaches. However, Weather2's villager AI will override MCA's villager commands.

Steps to Reproduce:

1. Put MCA and Weather2 in the same install.
2. Start a superflat world in Creative Mode and find a village (superflat due it being the most optimal world type for debugging).
3. Use the villager commands like "Follow me" and "Stay here", MCA villagers should act normally.
4. Spawn in a storm. MCA villagers should now be using Weather2's AI and taking shelter like with the normal villagers.
5. While a storm is in progress over the village, try to use the villager commands.
   5a. Try using "Follow Me", the villager will follow you, however it will be constantly fighting with the Weather2 AI causing the villager to run to the nearest building and then back to you.
   5b. Try using "Stay Here". The villager will ignore the command and just follow the Weather2 AI and hide in the nearest building (or by the door if already inside a structure). However, "Stay Here" will still be enabled and after the storm passes the villager stays in the spot where they hid until they are told to "Move Freely".

I came across this issue when trying to move a villager my player was married with into an underground storm shelter. Fortunately the villager got lucky and survived as the building they were in fell apart around them.

Another issue with MCA and Weather2 is with guard villagers specifically. With them it is the opposite issue, guard villagers do not respond to severe weather, guards will remain outside at their posts in a storm, they will stay outside even if a tornado is bearing down. While in context it makes sense for guards to remain out in a storm to guard the village, they should at least take shelter if a tornado is just about to hit.

I think a solution to the commands issue would be for when MCA is installed have Weather2's AI only work when MCA's villager move behavior is set to "Move Freely".

As for guards, I dunno

The mod appears to use its own AI system ( https://github.com/WildBamaBoy/minecraft-comes-alive/tree/1.11.2-master/src/main/java/mca/actions ) so unless I become randomly inspired to support that mod, I'd suggest just setting Villager_MoveInsideForStorms to false in Misc.cfg in the meantime.

But trying to detect its hold states might be a nice compat fix yeah.

Well, it's not like its a major issue. I can still accept it as it is for now.