Perhaps spoiler alert even 14 years after release : the Star Wars Jedi Knight: Jedi Academy 2003 video game.
I finished the game Jedi Academy once more yesterday, opting for the Dark Side when required to choose, and from then until the end, Kyle Katarn kept telling Jaden Korr (the playable character) that it was not too late and he/she could come back to the Light Side, even though he/she killed about 25 Jedi apprentices in the last level.
So my question is : what would happen to a Sith/Dark Jedi if he decided to come back to the Light Side after having done such horrible acts ?
I assume it wouldn't be as easy as "It's ok now, let's forget about it." and that he'd somehow have to pay for what he did, but is it known what would happen ? (a trial, a pilgrimage, exile, etc.)
As English is not my native language, I might be hard to understand, so feel free to ask more explanations !