Any original material made by Yami on Yami World is free for use with both free and commercial RPG Maker games.
Editing these scripts is perfectly okay as long as you still provide the proper credit. Any non-original content posted, linked, or shared on Yami World will require you to contact the respective parties for permission of use.
All people who asked me before was granted permission without any conditions, so I think this change won’t cause them any trouble. Sorry for this inconvenience.