The planet celebration montage added in the RotJ Special Edition is stupid and doesn’t make sense. It wraps up the story too neatly to the point of being unrealistic, while the original version is more open-ended. Palpatine is defeated, but that doesn’t necessarily mean the Empire is. And I always liked the EU version of events where the Empire falls apart due to infighting, but still exists in a fragmented, diminished form in later stories, being just one of many factions at work in the galaxy. That feels like a more realistic progression than that whole “Operation Cinder” business ending the Galactic Civil War within just a single year.
I can see a way in which the war ends quickly - but it depends on how loyal the military is to the ruling regime of Emperor, Vader, and the Moffs. If not very, then I can see massive defections quickly bringing back a Republican form of government. Or if the military is apolitical. But like you, I enjoyed the Legends EU take of the post-Endor situation, in which the military were strong supporters of the Imperial style government.
Then again there is post-TPM Legends and pre-TPM Legends EU - which differ on the composition of the Imperial military.
General Grievous is ridiculous. He should have never been brought over to live action.
There have been very few menacing droid designs in Star Wars, sadly.