Thanks to Toshiya Kobayashi, Keiko Suzuki, Yuhei Miki and Masahiko Umeno the jBPM Designer now supports Japanese. To switch from the default English to Japanese language support edit Designer’s web.xml, specifically change:
<init-param>
<param-name>designer.locale</param-name>
<param-value>en</param-value>
</init-param>
to
<init-param>
<param-name>designer.locale</param-name>
<param-value>ja</param-value>
</init-param>
and restart your server instance. The locale change will be picked up then.
Below is a screenshot of using the Japanese locale setting in Designer.
We are always looking to add support for more languages, so if you are interested in providing translations to your language of choice, ping us on IRC (#jbpm on freenode).

Thank you for highlighting this!
I’d also like to thank Keiko Suzuki, Yuhei Miki and Masahiko Umeno who worked on the translation.
Cheers,
Toshiya
I have updated the post to mention everyone who worked on the translations. Please thank them from me as well.