Are any students coming up with a process to prove their innocents when they get falsely accused? If I was still in school I would write my docs in a Google Doc which provides the edit history. I could potentially also record video of me typing the entire document as well or screen recording my screen.
I don't think there's any real way around the fundamental flaw of such systems assuming there's an accurate way to detect generated text, since even motivated cheaters could use their phone to generate the text and just iterate edits from there, using identical CYA techniques.
That said, I'd imagine if someone resorts to using generative text their edits would contain anomalies that someone legitimately writing wouldn't have in terms of building out the structure/drafts. Perhaps that in itself could be auto detected more reliably.