It's amazing what propaganda can do to change people's knowledge and perception of history. We're often taught that during WWII, the Allies were the "good guys" and Axis Powers were "bad guys." But even the children's "Horrible Histories" book series points out the fallacy of this perception, pointing out that in reality atrocities were committed on both sides. We hear lots about atrocities committed by Axis forces, but how often have you heard about atrocities committed by Allies? How often do you hear about the
atrocities committed by the Anzacs during the Kokoda campaign? The Nazi party has been universally associated with all things evil, but the fact was that there
were some good people in that party.
Oskar Schindler would be the most well known, due to the
Spielberg movie, but there were many others such as
John Rabe etc. And of course, Benjamin Netanyahu's
recent comments is just doing wonders for Israeli-Palestinian relations.

Heck, there's a lot of misconceptions about wars that are happening right now! The Assad regime is arguably a
greater threat to Syrians than ISIS. The recent tragedy in Parramatta was enacted by a boy of Kurdish ethnicity, despite the fact that the Kurds are actually
fighting on the front line against ISIS. Heck, just a few days ago I saw someone make an online post, criticising
NSW Police's motto, claiming that having a Latin motto is "foreign and unpatriotic." Ya know... despite the fact that English, a West Germanic language, is also foreign to Australia... and the fact that the words 'foreign' and 'patriotic' (as well as numerous other words in her full post) are of Latin origin.
So yeah, despite everything that's happened, it wouldn't surprise me if facts and information became diluted and corrupted through time. And it's often said that "history is seen through the eyes of the victors," so considering that the Jedi ultimately lost (thus allowing the Empire to rise), it's believable that they may have faded into obscurity. And the Sith were never about revealing themselves to the galaxy anyway. As you've said, probably nobody outside of Luke's personal circle would've been aware of what was happening with him and Vader. The fact that Vader was once Anakin Skywalker probably still remains a great secret to most people.