i'm not sure that changing the text of the final message would've actually helped us? since we were already assuming both that there was another layer, because we hadn't figured out what the hints even were, and also the game established that it was willing to mislead us. so "you're done! you've solved it! there's nothing left!" reads as though there is a cheeky wink afterwards (and naturally, we were greedy for MORE PUZZLE).
we can't really think of any way to actually solve this? it's probably fine as-is, but we still wanted to share our experience so you were aware.
the only thought i actually had about possibly fixing it, was revealing (one of?) the A hints, but that might also make their hintiness too obvious