It would be a retcon-albeit an not a popular to any Legends fans.(or I suppose we could make it a Legends AU). Also though the politics and worldbuilding of Canon and legends are too different. The lengths of the galactic civil wars are different, the Yuuzhan Vong don't exist in canon, etc... Even in ancient history it doesn't work-in Canon there is apparently a Sith temple on Coruscant from 5,000 years before the battle of Yavin which doesn't make sense in Legends as the Sith attacked Coruscant at that time but were not based there.