The I18n class has 2 constructors:
1. To present the string in the language that is specified in the user account
I18n i18n = new I18n(slingRequest);
2. For using the page locale:
Locale pageLang = currentPage.getLanguage(false);
ResourceBundle resourceBundle = slingRequest.getResourceBundle(pageLang);
I18n i18n = new I18n(resourceBundle);
Can you let me know how are you planning to trigger the workflow? Are you not using the servlet?
Thanks,
Kiran Vedantam.