The tag alias #71552 rainworld -> rain_world has been approved.

Reason: I'm not 100% sure this is the place to ask/request this but it is my best guess for the place to ask/request.
Like how searching "HTTYD" will load posts from "how_to_train_your_dragon" instead.

EDIT: The tag alias rainworld -> rain_world (forum #410304) has been approved by @Rainbow_Dash.

This is the right place! You did everything correctly.

The tag alias rainworld -> rain_world (forum #410304) has been approved by @Rainbow_Dash.