It's a bit of an aside, but it's worth remembering that "foreigners in Japan" is anything but a homogeneous group, and they have very different experiences and very different resources at hand.
Some of the most common foreign groups coming to Japan are Chinese, Korean and Philippine. They will rely mostly or only on sources written by members of their own ethnic group, and will mostly or only interact with others like themselves.
Arguably even many Westerners will not primarily rely on English sources. After all, the information on taxation, driving licenses, retirement funds, visas and so on differ greatly by country. Even members of very small minority groups such as myself (Swedish) rely equal amounts on general "foreigner info" in English, and on forums for Swedish people abroad in general.