IIRC - IANAL
First, the libel has to be false. The truth is a defense.
Second, generally, the falsity has to be deliberately untrue, or so obviously wrong that it was recklessly negligent to print it without checking its veracity.
Most libel contains enough truth that the suing party probably does not want the details examined under a microscope, as would happen in court.
Finally, there’s a “close enough” defense. The example I heard - Suing because you were called a horse thief doesn’t work if it turns out you in fact just stole the saddle and bridle…
Where can they sue you? Well, it depends. What’s the point of suing you in Canada, if the result is a judgement they can’t collect? Not sure if a judgement in Canada is recognized in France, or if they would have to sue you there. Of course, if you have significant assets in Canada, you may want to respond to the lawsuit. Plus, they would still have to serve you.
Lots of fun all around once lawyers are involved. Odds are they won’t be. The first thing any lawyer will tell a client is “even though you haven’t a hope in hell of winning, we’ll send a sharply worded letter and see if that makes them stop.”