Can you please describe your use case in more detail - looks like you are trying to build an AEM service that uses this API. If this is the case - you need to use this API:
http://docs.smartling.com/pages/API/
I see this supports a Restful interface:
"The Smartling Translation API is a REST-like API that allows you to access functionality provided by the Smartling Translation Management Platform using defined HTTPS requests and structured JSON responses. "
You can build a custom AEM service to interact with this via a restful service. See this example as a guideline:
Creating Adobe Experience Manager services that invoke third party Restful web services
