You are right about your MtDNA results not being the same as your cousin's. In fact, unless your father and your cousin's mother were the children of sisters, their own MtDNA results would not even be the same.

As for the question as to whether your cousin's results show whether the great great-grandmother was born in Ireland, my guess would be that the Irish great great-grandfather could have married a French-Canadian woman, but I don't recall being told that my own MtDNA test results were country specific as you are describing hers as being.

In my own case I assume that my post-1600 ancestors were from the British Isles yet I have matches whose families have never left Germany or Scandinavia as well as some from Canada who have never had family members in the US. Drawing conclusions about relatively recent ancestry through MtDNA testing results can be a real challenge.

Good luck!

Michael