There's a website that has all japanese manga volumes release dates: http://www.taiyosha.co.jp/comic/ Full list of June manga sorted by date: http://www.taiyosha.co.jp/comic/comic1206_listdate.html
Maybe BU can use that list to update Status in Country of Origin field automaticly? I don't know whether it's legal or not.

Example list entry:
06/04　　集英社　　 ＢＬＥＡＣＨ　 －ブリーチ－　 ５５　　久保　 帯人　　\420
translates to:
June 04, Shueisha, Bleach v55, Kubo Tite, ¥420

What's more, final volumes are marked with (完). So it's easy to know whether manga is Ongoing or Complete. Example:
06/16　　竹書房　　 ベルベット・キ ス　４(完)　　ハ ルミチ　ヒロ　 　\650
June 16, Takeshobo, Velvet Kiss v4 (Final), Harumi Chihiro, ¥650

Mangas that're marked as "Adult Content" in Japan have (成) tag. It's mostly hentai, even Velvet Kiss is not marked as "Adult". Example:
06/12　　大都社　　 (成)完全凌辱遊戯 　４　　杏咲　 モラル　　\1000
June 12, Daitosha, (Adult) Kanzen Ryoujoku Yuugi v4, Anzaki Moral, ¥1000