Any campaign world should be full of old retired adventurers who had their glory days years before the current crop of young hopefuls started trying to make their fortune. They should have all sorts of harrowing tales to tell. And possibly still be suffering from the trauma.
Rather than just being a source of rumours, they can have their own stories about what incredible things they once got up to. Here is where you can let your creativity and worldbuilding run amok. You can't control what the PCs decide to do in your setting, but you can write stories you want to write, and have them appear as background tales told by people who lived through them.
Commentary by memnarch (who has not seen the movie)
Palpaclone found that sword and lost it? .... Sure why not. It's a little less ridiculous than coming back as a clone, except for the part where said sword probably fell down into the clouds around Cloud City. So, you know, the main reason the sword got lost in the first place.
As for Palpatine bumping into Kanata 30-40 years ago, that sounds completely like a comic thing. That'd put things around the time the second Death Star blew up to put the timing afterwards, and I'm fairly certain he didn't sneak into the shuttle Luke used to escape. Before that point has the problem of Palpatine just happening to cross paths with Kanata while he's busy running the Empire. And then getting punched out sufficiently for Kanata to escape with a lightsaber, all while avoiding the troopers and support staff that'd be around.
Of course, Kanata could be misremembering how long ago it was, having other memory problems, and this was all about Palpaclone, but where's the fun in questioning that? Time mysteries are much more interesting.
Transcript
Rey: I want to talk to Darth Kanata.
GM: Sally! Here’s some extra background about Kanata.
Darth Kanata: Yes, Rey?
Rey: You said how you got Luke’s sword was a question for another time. It’s another time. Spill.
Darth Kanata: Things get lost in this Galaxy all the time. Orbs. Whole planets. People. Swords.
Darth Kanata: Some of them get found... in the wrong hands.
Darth Kanata: Our little friend, Palpatine.
Rey: Palpatine?! When was this?
Darth Kanata: While back. Thirty, maybe forty years. We had some unfinished business to settle.
Darth Kanata: Bumped into him, walking the Galaxy. Fool didn’t even recognise me.
Darth Kanata: I knew that sword was trouble, so I took it. He disagreed, but my fist had a good closing argument.
Darth Kanata: I call it Force Persuasion... with extra persuasion.
Darth Kanata: After that, I smoked so many death sticks I nearly forgot my own name.
Darth Kanata: You know you smoke too much of that crap, that crap robs you of your own ambition.
Leia: This is why we don’t invite you to diplomatic functions.