Yeah, I just spent some time trying to figure this out after seeing your post. I have not noticed a flaw described in this way on nearly any other test that I can think of, and I've been through a few of them. I believe your characterization of the flaw may be a little off. The flaw in reasoning doesn't lie in the fact that the guy is "confusing" a contended true statement with a contended false statement, but rather, by failing to distinguish one from the other, he commits the exact same reasoning flaw his opposition had just committed.

My conceptualization of the flaw being described in (E) would be something along the lines of: Person A argues that a lack of evidence for a position is proof that the position is false. Person B would then argue that some evidence to support a position would prove the position true. The arguments are of equal strength(weak) and by B responding to A in such a way, he didn't "distinguish between a true claim mistakenly believed to be false from a false claim mistakenly believed to be true"; there's no difference, or distinction, between the arguments.

This could be off as I didn't quite address the claim, but this is all I could come up with for the flaw described in (E). Let me know what you think because I'm stuck on this as well.

A-->B-->C-->D

Whatever variable is negated after your original chain is established, start at that point and run it backwards (right to left), negating as you go. Ignore everything to the right of the negated variable.

If C is negated, then you now know -B, -A. Because the variable C is negated in this example, you learn, per the contrapositive, that B and A are also negated; however, you cannot infer anything about D. Less confusion than having the entire contrapositive written out, IMO. Whatever variable is reversed (positive to negative or negative to positive )in the logic chain, start at that point and reverse(positive to negative or negative to positive) everything going backwards in the logic chain.

If original logic chain in an IN/OUT is A--> -B --> C --> -D --> E and D is "IN", then, starting at D, you run the logic chain backwards to find -C, B, -A. So, you'd have IN (D,B) and OUT (C, A); you'd know nothing about E.

Is this what you were looking for or did I misunderstand your question? Hope this is somewhat helpful.