You would translate whatever is within quotes, but good point, when you see a json strucutre like
{
id: "abc",
name: "ABC",
description: "xyz",
info: "xyz"
},
you would leave the the as is. Maybe best is to look at the Japanese translation file: https://github.com/droolsjbpm/jbpm-designer/blob/master/src/main/webapp/i18n/translation_ja.js
as that should give you a better clue on what those guys did.
Thanks