From your second link above:
"The Oxford Dictionary defines an auteur as ‘a film director who influences their films so much that they rank as their author’... "
But again, he already IS the author, so that doesn't count. Someone else has to write it first. Basic logic.
The other two are about Auteur Theory, which generally differs from or conflicts with the actual definition of auteur anyway, but is more subjective than anything else.
In some ways, so long as the director changes things around enough from the concept as written that they end up with an almost completely different film, that makes them an auteur... technically!
Tarantino does have considerable genius evident in his work... but ^that's not it!!