Again, Miguel Ribiero is a guy who lives in Portugal and writes in both Portuguese and English and has sold his work to Brazilians. He said that Brazilians seem to prefer reading his work in English. The logic of why? yeah, don't ask me. I was surprised by this myself.
I HAVE seen similar occasions with drastically different Spanish dialects though. Puerto Rico and Baja California have very different Spanish dialects.... and I used to know a couple who had to learn the hard way how different they are.
They would sometimes switch to English... just because of being confused about dialect differences.
Hm... maybe it's a matter of the books being used as reference materials? A book as a reference material would be less useful if you need to ask the author what the phrases mean.