Hi,
sorry for late reply, here a guide to translate Easy Profile

To translate the string "Login with facebook" you can follow these steps:
- Go to Extensions->Languages->Overrides
- Filter for your language, in your case French
- Click to new Button
- In the parameter Language Constant put following code COM_JSN_LOGINWITH
- In the parameter Text put your translation (see screenshot)

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and in general to create your translation for entire component:

Translate Easy Profile
Easy Profile use Joomla MVC model so you can translate it as all Joomla components:
- copy file /language/en-GB/en-GB.com_jsn.ini into /language/your-LANG/your-LANG.com_jsn.ini (for example /language/zh-CN/zh-CN.com_jsn.ini )
- translate new file with a normal text editor
- same way to traslate backend but language folder is /administrator/language/

Translate Social Network Plugin
Here a docs http://docs.easy-profile.com/index.php/article/social-network-make-your-language

To translate