Using Freshdesk, you could configure your self-service portal such that customers would be able to view the portal in different languages. To configure the same, please navigate to Admin--> Account --> Helpdesk Settings --> Manage Languages. You could add to the list of Supported Languages. 

Once that is done, you would have to choose the "Visible On Portal" option so that the languages are visible to customers on your support portal from where they could choose the Portal Languages.

This feature is available from the Garden Plan onwards in Freshdesk.