Translation of the pages and forms are done in the Guest Self-Registration definition, not (yet) in the global translation.
You can translate the pages, and forms under: Guest - Configuration - Pages (in ClearPass 6.4) or Guest Self-Registration (6.3 and below), then edit your self registration.
On that page you see all components that make up the Register Page, Receipt Page, Self Service Portal and login page. You can create a copy of the default page and translates all required components.
For multi-language environments, you can create different pages per language (or company, or country, or location, etc...).
Herman