"...why did Kurokawa have two different forewords: one for foreigners blaming Japanese culture and one in Japanese talking of regulatory capture?"

Psst, Dr. Kurokawa, Dr. Kurokawa... Rick, I don't think he's following this thread right now. In the meantime, though, if you need to make an informed guess, there are a few facts that might be of help:

1) The English summary came out at the same time that the Japanese language main report and summary did, which under normal conditions defies the know laws of physics.

2) The foreword is not the only difference between the two texts. In fact, the website (http://naiic.go.jp/) now has the following disclaimer (in Japanese):

"Incidentally, as already indicated in the English version Executive Summary, this report was complied in Japanese, so if there are any discrepancies between the Japanese and English versions, the Japanse version is the official text."*ed. LOL*

3) The text of the English-language foreword--okay, "Message from the Chairman"--has the look and feel of a document crafted from the near-though-not-quite ground up by a native-English speaking, professional writer rather than a straight translation from a Japanese language document.

I leave you all to connect the dots.

"And why is that discrepancy not itself more of an issue within Japan?"

I'm pretty sure that the national news and political news desks and their kisha club folks don't read the Guardian. So maybe you should just be a little more patient and wait for the Asahi/Togo-Masakosama boomerang, which appears to be happening with the piece from Mr. Nakai, the Asahi correspondent in New York.
But then, I don't think it's a big deal in the first place--so Kurokawa vented? meh--but maybe it's just me.
I'm just glad that I made my assertions about some facts around the documents stick.

BTW I'm very happy and reassured that we've come to a mutual agreement on our little argument. What I can't get over, though, is one specific reason the full report gives why TEPCO didn't build that seawall. It wasn't the money. In an otherwise not very favorable report for TEPCO at that. Just goes to show, facts are usually stranger than the truth.