> As an aside for anyone who has found the secret area, one of the pictures told me to come back after I had done something with the Gwuils. I restored the Gwuils, but found I couldn't get back. Was this just another joke, or didn't I look hard enough?

Not a joke. Did you get back to where the secret area is and just couldn't find it again, or did the game prevent you from actually getting there in the first place? If you wait too long, the game ropes you into the end-game sequence that you can't break out of, but the bit of the secret area you were told to come back for becomes available a bit before you hit the end-game sequence.

It's a minor thing, but it's a spoiler, so the secret area code makes sure you've played through most of the Llagimlyn section before letting you see it.