To be honest I don't understand the obsession about documenting things that are done to the painting. Going through that section of the museum I felt like the curators cared more about showcasing their efforts to store the painting than the painting itself.
The painting today is different than it was fifty years ago or a hundred years ago or from the day it was completed.
It's common for paintings to be modified after completion, either by the creator or by the current owner. Whose version are you seeing? What are the possible versions?
Anyway, the best part of a museum is you don't have to look at the things that bore you