Not only do you not understand metaphysics you are clueless as to (un)decidability and its practical applicability.
And on top of all that you are rather uncharitable.
That's why you can't tell I've been practicing Socratic Irony throughout this entire exchange.
The notion of undecidability is well understood and well formulated: https://en.wikipedia.org/wiki/Undecidable_problem
It is a meaningless to even speak about the "decidability" of Metaphysical questions until you define the QUESTION in formal logic.
It's a problem of satisfiability which corresponds to the problem if criterion in epistemology.
Quoting the relevant context (that you do not understand):
If you insist on rigour and clarity then put your money where your mouth is and formalize it.Whether a particular theory is decidable or not depends whether the theory is variable-free or on other conditions.
Good riddance. Let the idiots remove themselves.