Roblox is not a game engine. It’s a child labor farm. Stay well away.

There are a lot of simple tutorials for Godot. It’s not hard to get into.

I haven’t played with 2D particles, but in 3D you can make the spawned particles not behave as if they are parented to their spawning node. It allows you to spawn them in a moving area, but not move with the area.

I can’t remember the option, but it’s in the inspector.

The downside for something like this is that the area outside of the spawner won’t have any particles, so it will look like it just started raining anywhere you go.

You could set up particle ‘tiles’ that are pre-computed and start full of rain, then just toggle them on and off depending on player position.