How do you apply the Fälschungsmöglichkeit to magic?
You cannot because it cannot be applied to the fade which is a world of dreams as such you can't define magic as a form of science.
How many time you would try to convine others that magic is a form of science?It would be better to convey that we agree to disagree.
You're going to have to go in detail what "Fälschungsmöglichkeit" is, because even Google has problem finding what it is.
Also - you're completely confusing things. I mean, aside from being guilty of what I described before (conflating our world with world of Thedas, which is different to ours and where magic is demonstrably real) you also seem to be thinking that "science" is some sort of category of reality - like where all the physical things and phenomenons that are described or explained by science are, ultimately', 'science'.
But that's a kindergarten understanding of science. Science is not a category of reality - it's our way of knowing reality. A tool. "Scientia", from which the word 'science' derives, literally means "knowledge". It is, by dictionary definition, "a field of study concerned with discovering and describing the world around us by observing and experimenting."
Is magic in Thedas part of empirical reality? Yes, there's evidence of magic existing beyond any reasonable doubt.
Can you observe and experiment with magic in Thedas? Of course you do.
Can you discover things about magic in Thedas? Absolutely.
Can you describe magic and what it does or its effects? YES!
Can you create predictable models and consistent, testable results (spells, enchantments, rituals, summoning circles, magical techniques, etc)? By all means yes.
Therefore magic - if it's part of the world like in case of Thedas - naturally can be part of scientific inquiry. The knowledge and understanding of magic can be based on scientific method; it's just that their finding would be different to ours. In fact this is what was happening in Elvenhan, based on many codexes we find in Vir Dirthara. And even Solas, a Fade-Nerd and Dreamer Extraordinaire, says that to extrapolate truth from the Fade you need logic and reason and generally displays a very scientific mindset.
Like... because Fade is a 'stuff of dreams' hardly means anything - it only sounds as if you thinks that dreams can't be studied scientifically for some reason. Thing is that they ARE and the fact that they can be deeply 'symbolic' means little, because that symbolism is still determined by the way our brain is built or has been shaped, and therefore can be studied. It's not 'magic' by any means. Neither are rainbows, or lightning or air, which at one point or another were thought to be "magical". They can all be studied or described scientifically, without losing anything.
The problem with your reasoning is that you seem to think of "magic" the way we think of - as a concept that is useless when you try and apply it to most fantasy worlds. Nowadays we generally think of "magic" here as anything that is not confirmed/yet to be confirmed by science - which, if you think about it, is not only extremely limiting, but almost incoherent. It's basically like calling non-smoking a habit and NOT collecting stamps a hobby. A vacuum. A wishful thinking. A category of things we want to be real, or simply don't understand, even if it turns out that many of those things we don't understand can be easily explained by science.
But magic in most fantasy world, as well in Thedas, is not just some form of wishful thinking, or a way to describe things people don't understand - it's a real, palpable force in the world, on the same level as (and sometimes stronger than) gravity or electromagnetism. It's real and true, even if what's "real" in Thedas can be overridden by a powerful enough will. So yes, you can totally apply scientific method to it and understand magic that way.