Try questbool MedicalDiaperUnlocked it should work. NG+ would be a fun idea but would probably need a lot more work that what I'm willing to engage with for a game near the end of it's lifecycle.
Hey, kind of have another problem... I bugged the Missing Formula quest somehow by having more than one of a given Formula Page I believe... Also I somehow skipped fourth from last Story achievement, the one just after Unveilling the Truth.
