This "simultaneous isekai as cute girls" is kind of nice at 625 chapters... the MC's Tohsaka Rin persona ate Goetia and then turned the 4HGW into a battle between beasts, well, there was still a grand saber and a gilgamesh. Final boss is her own Ereshkigal who turned into beast too, who let her kill her through the power of friendship lmao
You'd have to figure out how it would compare to existing materials we already have, though that is something you'd likely need to hash out with Ken as I don't even know where to start.
Honestly, Decibels and Ken and the ones you likely need to be talking to about this, as Decibels seems to be managing the project and it's Ken's setting we're playing in.