needs more explication

The film seems to be demanding that the viewer take it on faith that Norton is a complete trickster, and not a real/paranormalist magus. This view is derived from the fact that, whenever Norton does explain a trick, there is a "normal", if tricky and clever, explanation. But he is never required to "tell the secret" about his most spectacular acts.

As others have suggested, the gambit of Norton as "mere stage magician, after all" simply does not justify or explain the truly anomalous nature of his greatest effects - which really are so non-mechanical that they can only be fleshed out by cgi. Their cinematic ultra-smoothness only serves to plant in the viewer's mind the unshakeable conviction that these acts, at least, must be real.

Of course I'm talking about the truly apparitional manifestations - the "dead" dutchess, the bilocating and non-solid male child, and finally, Norton's final stage appearance itself, when the magician himself is a solid-appearing, but oh-so-ethereal, permeable, and ultimately vanishing, apparition. The inevitable feeling is that these manifestations simply could not be faked: they must be the real deal, no matter how long Norton protests that they are simple trickery.

The film does not supply enough NON-suspension of disbelief for viewers not to puzzle over Norton's greatest wonders. It does not supply enough convincing data that Norton's supposedly non-paranormal tricks are really non-paranormal.
The mechaniistic-illusionary explanation for these anomalous paranormalia falls flat on its face, IF it is trying to tell us that reductionist skepticism is the only way in which to view Norton's tricks. Norton's/the film's effects were much too realistically realized to come to a non-paranormal conclusion.