That’s true. I hope you still consider the Han death flashback, though!
And to answer your last point, it’s mostly due to cadence and the varying volume/EQ of the audio across different sources and even scenes.
EDIT: Before I forget, the only place where Rey can comment on her feeling responsible for Leia’s death is right before she says “I’m never leaving this place, I’m doing what you did.” It would have to replace her comment about her vision on the dark throne. Just spit-balling some ideas here: “Leia is dead because of my moment of weakness. It’s not safe to be by me.” or “If I hadn’t lashed out at Ren Leia would still be alive. It’s my fate to cause pain.” I actually think the first one lines up perfectly - it was a moment of weakness that caused Luke to go to Ahch-To originally, as well.