Hmm, I remember the old internet bulletin boards. When I first read the books, I then had a look at the annotations at the L-Space wiki and thought, "Ahh ... so
that's what I missed."

I didn't always cotton on to what Terry was getting at.
As for fans insisting that he was "wrong" about things he'd written ... sigh. Why? Give the man his due: they're his books. Saying he's "wrong" isn't helpful in the least, and just makes people look conceited and arrogant. I'm not surprised he moved away from it, but I think it's a great pity.
By the way, speaking of Discworld locations corresponding to real-world ones: does Llamedos have Welsh characteristics? It certainly seemed that way after "Soul Music", but in "Rising Steam", Llamedos is described as "sensibly dwarfish". Obviously Wales has no dwarfs, but is there Welsh folklore or legends about dwarfs? Also, Llamedos's economy in RS is described to centre around mining, fishing and logging. Is that the case for Wales, too?