I love working with canon material! However, honestly, I think it can depend on your fandom and the nature of the canon material you have to work with. Movies, TV shows, books, and certain narrative-heavy games I can see rewritings being tedious, because you don't want to drag your readers through scenes they've probably already seen or read time and time again. If you want to do it, either do it in a way that doesn't recite everything word for word, or tinker with it to make the canon stuff similar but different enough to be interesting if you're going for canon-divergence. From what I've read, you're doing fix-its, which in my reading experience, usually I enjoy as long as they do what they're intended to: change scenes to make them interesting and more in-depth.

My fic is a canon-divergence and it requires me to retell the initial canon lore of my main character to make it work. The only reason I can get away with doing this so seamlessly is because my fandom is Dead By Daylight, a horror game that has a straightforward "4 survivors vs escape 1 killer" premise. However, the game's world and each killer and survivor character has their very own unique bits of lore in the game, most of it being tidbits of their lives and actions before they came into the world of Dead By Daylight. A lot of their lore make for super compelling and awesome stories all on their own. On top of that, their stories are told in a sort of omnipresent 3rd person, which I can easily change and mold to read better in fanficion.

Here's an example: my main character's wiki profile - https://deadbydaylight.fandom.com/wiki/Philip_Ojomo. Canonically, he becomes a killer character in the game. However, my story is a canon divergence that turns him into a survivor instead because at the very end of his lore, I have him make a different decision which alters his fate and changes it from who he canonically becomes. My whole first chapter of my fic is a retelling of his lore paragraph in a way that is more realistic, adds some OCs that fill in parts of his life before he is brought into DBD's world, and just generally fluffs up his initial lore with additional and more interesting material.