Okay, how do you determine the difference between fantasy and the supernatural, other than definitional differences?
A fantasy cannot be evaluated by any branch of Philosophy, what the supernatural ,and other truths can be.
For example, the question of "How many men in the Legio IV Macedonica who fought in the Batavian revolt were named ‘Marcus’? Is not a science question. It is a question for the Philosophical branch known as History ( which is why Historians also get Ph.Ds and not D.Hist degrees)
The answer to that question has a real, numerical answer, but it cannot be exposed to the scientific method. The answer is determined by historical analysis, but the answer is real. There is no chemical composition for the name Marcus that could be analyzed in soil samples from the area, nor ‘Marcus’ particles that can be detected.
Likewise, the evaluation of the truths of the supernatural , that falls into the realm of the Philosophical branch known as Metaphysics.
The tools used in each branch are entirely different. Using the tools of Natural Philosophy to evaluate truths of Metaphysics makes no more sense that trying to build a Marcus Particle detector to evaluate Roman History or trying to detect ‘Justice’ via a blood sample ( Ethics)
In addition, you are correct that, the evaluations in every branch have produced errors in the past, science included. But as the tools for each branch develop, so does the depth and validity of the evaluations.
But the tools, and the truths evaluated, as the distinct province of each branch of Philosophy.