On the question of Japan's civilisation homogeneity, the BBC ran an important series published online here with a valuable link list of related articles. The article supports the statement from lecture this week that 99% of people in Japan are ethnically pure Japanese and non-ethnic Japanese are denied citizenship even when born in Japan.
One especially helpful edition is here. Click on the slideshow within this article for a useful sample of opinion on immigration from ordinary Japanese.
These articles are relevant to our understanding of the need for civilisation translation and the difficulty presented by the necessary indeterminacy of radical translation.