http://www.zotero.org/support/ja/supported_languages

This link explains the way to tweak config of zotero to export sources in English. It takes just a few minutes without any trouble.If you don't want to install new browser this would be a solution. Last semester, I had a chance to write some papers for my sociology class but zotero doesn't support the American Sociological Association's style. I looked for the way to create own style and find the article explains it.

Find and edit CSL citation styles
http://editor.citationstyles.org/about/

Before, a person need to code by hand to create new style but the tool above enable a person to create a style more intuitively. It may look some how difficult especially if a person start to create new style from scratch but by searching similar style, editing wouldn't take much time. Also, the webpage provides more styles than zotero so that the next place to look for style after zotero should be this page.