A new book by conductor and scholar Roberto Duarte entitled Villa-Lobos errou? looks at the often chaotic state of Villa-Lobos's scores. According to Duarte, who has published careful studies of Villa's orchestral scores in the past (the two-volume Revisão das Obras Orquestrais de Villa-Lobos in 1994) notes that "his mind was much faster than his hands." Villa-Lobos wrote so many notes that it would have required a super-human to keep everything perfect. As Duarte says, the composer was "intensely human."
The book is trilingual: Portuguese, German, & English. I'll see if I can order it from the Great White North, and report back here. It's for sale at Algol Editora and Loja Classicos.