I tried searching 日本東京都足立区足立２丁目 (google suggestion) and your app doesn't accept.
we're able to get all the computers in the world to be more or less on the same network but we still can't figure out encoding problems from 1982
edit: I messed up writing this, should have been 足立区六町２丁目. Using http://nice-map-urls.herokuapp.com/japan/tokyo/adachi/rokuch... I get the right spot, but the search box doesn't seem to work for me(but I am behind a very high-latency line, it might be my connection that is borking)
second edit: seems that the resolution is around ward-level(even when searching romanised addresses like "2-10-3 Honkomagome, Bunkyo, Tokyo", a search which works in google maps) From an intuitive standpoint, there should be no reason for this not to work, there's nothing particularly weird about the address format. I dunno