Just a suggestion that villagers go into houses when a siren activates near them like how a bell works.

Dupe of #505 but worded better. I second this.

As a temporary solution, are you able to use the weather sensor to trigger a bell?

is the weather sensor in the game in 1.18.2?

Yes. It's called a weather sensor. I donno if craftable yet or not tho.

to add an Suggestion to this thread villages should have a storm shelter for the villagers to go into instead of their houses

I don't know if the storm shelter thing is easy to implement. Might have to override villager default go indoors function or add a second function that's only called when the tornado siren activates.