When should an author retract their paper as a result of misinterpreted results?
Outside of ethical issues, I'd argue that the only time that retraction of a paper is warranted,  is when there is a methodological error that is so great that it completely invalidates all or almost all of the paper's key results. For example, if a paper is supposed to observe phenomena A, B, C, and D, I wouldn't retract the paper if the experiment that was supposed to measure D was done incorrectly, but the results of A, B, and C remain unchanged. A correction or erratum should suffice in such cases. However, if a paper was trying to derive X, Y, and Z, but faulty assumption Q invalidates all of the derived results, then that paper should be retracted.