XLIFF translation import doesn't work

I have some issues with the XLIFF file for the translations.

At first we had some error message when we import the xlf file.

Then we test, importing without changing the name of file. We stop to have the error message, it seems to import correctly but we don't see any of the translations in french we imported.  Can you help us with the importation? (1)

We change the source language and the contend directly in Notepad++ as the translation company need source language "en-CA" to work with his software. 

As we are located in Canada my translator company want to know if there's a way to export XLIFF with source language "en-CA", as his data base is in this source language. Is there a way to configure source language in "en-CA"? (2)