Sadly there isn't any other alternative. Remember that Project M made alot of sacrifices to make alot of thingswork.
Turning them back to CI8 will increase the file size.
The PMBR had to make a CSP quality sacrifice (by making them CMPR) in order to have space for Mewtwo, Roy, and Alt cosmetics.
So no, you can't make them back to CI8 without file size issues.
I have to agree worh him at this point. So sorry