I think the Old Ben’s line should feel more softer for the scene imo
See, I thought the same thing. That’s why I had the generative solution at first. But I need the voice to be instantly recognizable. The same exact delivery helps people recognize it. Or else people would be wondering: “Who is speaking to Luke right now?”
Is it possible that it’s more of a volume thing? I wonder if it were quieter if that it would be better. The whole point of the line is that “letting go” is the final step in becoming a Force ghost. You have to let go of all your earthly attachments. Ben is essentially telling Luke that everything will be alright without him; his legend will make the galaxy rise up in the next movie.
Regarding DJ, I’m not sure of any tools that let you change individual elements of what’s on screen. Maybe it’s out there and I’m just not aware of it, though.