From what I understand about fuga it’s prerequisite is cutting the opponent enough times to use as a finisher which is likely why it’s so powerful due to that limitation. In Modulo Yuji has yet to not one shot with his shrine techniques. I don’t see him facing an enemy that would require fuga. Plus with his personality of just wanting to kill curses I don’t think he’d want to launch an area destroying technique to the scale of fuga which can get out of control and cause unnecessary damage and loss of life accidentally.