(As a non-native speaker) several bits of the Japanese transcription were just Japanese-sounding noise, and the prosody was completely all over the place in the bits that were actually Japanese. The dub does get across most of the things being talked about, but I wouldn't consider it an acceptable dub (even for most of the bits where it is actually in Japanese).
I wonder if reason is that the dubbing works better between more similar languages and struggles when dealing with disparate languages. I don't speak Chinese or Korean, but it would be interesting to see how well their dubs are.
Can you do another video into Japanese, to see if it's just an issue with the Paul Graham video? Also, how about translating from another language to English?