What else could be the phrase “knot of disgrace for the human race” mean, in a proclaiming Christian context? Especially since the site claims it was “based on the parallel made by Saint Paul between Adam and Christ. Saint Irenaeus, in turn, made a comparison between Eve and Mary” ?
It means what it says, not what you want it to say. It does not say she undoes the sin (or have I missed that quote?), it says she undoes the knot of disgrace.