Dunno about the visualization, but it should be fairly simple to extract each labels data out into individual files. From there, could generate a table of each jump entry from within that label. Then join them. . .I doubt Ren'Py has a built in function for this (you'd probably have to delve pretty deep into AST shit or make your own parsing script) but a variant which creates a tree of labels based on how they follow each other in the game, and optionally outputs some sort of a visualization based on that would be insanely helpful.
View attachment 502875
Something to work on if anyone here is familiar with Ren'Py and has too much free time on their hands.
Edit: having each label as its own file would also help identify which variables are referenced for each scene.