Fantastic stuff, and it reminds me of why I liked DE so much. ! Young Han and Leia fighting together! Leia using the Force in a non-stupid way. A great design aesthetic too - really Star Warsy.
But it undermines ROTJ. And ROTS. Which is entirely bad, except when Disney does it.
Somewhat, but for me ROTJ was about the redemption of Vader and Luke becoming a Jedi, so DE does not completely undermine it. Now if you add in the PT nonsense about prophecies, the Chosen One, bringing balance to the force and all that garbage then, yes if does undermine ROTJ.