You can completely change the content of whole pdf by using "renderPDFForm" operation under service "FormsService". in this operation there is Template category where you can set the Locale.
And if you need to change the other workspace options like Complete, Save as Draft , you can then import workspace ui project and then change apppropriate values.
Thanks for the response, but I was not talking about PDF output. I'm referring to the Flash-based user interface that exists in Adobe Process Management workspace, especially the action buttons for user tasks. There only seemed to be one label for those. For a bilingual form, we would need a way of specifying action labels in multiple languages.