Sort a view by country - according to the translated countries
Your problem is that views uses SQL to sort, since that is a lot easier and faster and it otherwise would be required to load all the records and sort them with PHP, before selecting which to show, which is a massive resources waste if you have a lot of records and use paging.

A simple solution to this problem, is to create a work around. Since the country names is stored in english, you can create a field that you hide from the user where you store the French country name. You can then in your view use this field when sorting. You would need to write a bit of code - in a custom module you create - to hide the field in the UI and automatically set the correct value based on the country the user selected in the interface. This can all be done with hook_form_alter.