Perhaps I’m misunderstanding you somewhere, but it seems that the requirement you need on defeaters is much stronger than the No Indescribable Hellworld hypothesis.
For a bad argument to be seen to be flawed by a human, we need: 1) A flaw in the argument to be describable to the human in some suitably simplified form. 2) The human to see that this simplified description actually applies to the given argument.
Something like the NIHH seems to give you (1), not (2). I don’t see any reason to think that (2) will apply in general, but you do seem to require it.
Perhaps I’m misunderstanding you somewhere, but it seems that the requirement you need on defeaters is much stronger than the No Indescribable Hellworld hypothesis.
For a bad argument to be seen to be flawed by a human, we need:
1) A flaw in the argument to be describable to the human in some suitably simplified form.
2) The human to see that this simplified description actually applies to the given argument.
Something like the NIHH seems to give you (1), not (2).
I don’t see any reason to think that (2) will apply in general, but you do seem to require it.
Or am I missing your point?