Briefly on this one: it is most likely a case of post hoc sed non propter hoc (West Wing fans will spot the allusion, I hope). In my recollections there is no reference in Grant v Tortstar to Quebec or civilian ideas.
It is based squarely on Reynolds v Times Newspapers (England), which itself borrowed heavily from Lange v ABC (Australia). A couple of years ago I did some research on the Australian origins of responsible journalism and traced it back to parliamentary debates
surrounding the Defamation (Amendment) Act 1909 in NSW. No hint of civilian thinking anywhere along the way, I seem to remember.
What is very interesting in Reynolds is that it was originally conceived of as a form of qualified privilege. But QP emerged historically as one (objective) way of rebutting the presumption of (subjective) malice.
So, what the defence seemed to say, at least at first, is that when you publish to the world at large the way you rebut the presumption of malice is, inter alia, by proving you tried reasonably hard to get it right, even though in the end you didn’t. What
is fascinating is that the very same story happened in France a century earlier. Liability in (criminal) defamation was originally based on presumed animus iniuriandi, like the rest of the civilian tradition - which means the accused had to prove ‘good faith’
to get off the hook. But, by the turn of C20 it seems, courts had interpreted good faith as entailing ‘caution’ on the journalist’s part. I.e. again you rebut malice by proving diligence in fact-finding: the very same idea you will find almost 100 years later
in Reynolds. Yet no visible borrowing whatsoever that I could identify there either. Post hoc…
You might consider the new defamation common law defence of "responsible communication on a matter of public interest" as an example of this "trend". Traditionally being "responsible" or "reasonable" did not exonerate a defamer from liability
for defamation at common law, unlike the civil law's "fault" requirement for liability in defamation. Now being "responsible" is a defence in the context of mattes of public interest, even if the material is false and defamatory and not protected by one of
the other defences. A small example, perhaps, but it might be useful to note it.