And I will put enmity between thee and the woman, and between thy seed and her seed; they shall bruise thy head, and thou shalt bruise their heel.'
Biblegateway.com has the RSVCE now (way cool!) and you might take a look at the footnote on Gen 3:15. The direct link is here.
Your link actually proves the inaccuracy of RC’s Latin translation. It also talks about mistakes, so you didn’t help your case by any means. From Hebrew to English CynicalBear is spot on.
” The Latin Vulgate has the reading ipsa conteret, “she shall bruise.” Some Old Latin manuscripts have this reading and it occurs also in St. Augustine, De Genesi contra Manichaeos, II, which is earlier than St. Jerome’s translation. It could be due originally to a copyist’s mistake, which was then seen to contain a genuine meaning—namely, that Mary, too, would have her share in the victory, inasmuch as she was mother of the Savior.”
http://biblehub.com/interlinear/genesis/3-15.htm
Translating languages is always problematic, but RC’s go from Hebrew to Latin to English meaning word and meaning possibly being lost two times. Instead try one translation and go from Hebrew to English less chance for loss of meaning.