((You mentioned a divergence from time lines. How is it possible to measure such a divergence?))
The measurement for worldline divergence is an observation variable isolated to the distortion unit. An effective analogy would be a “gravity radar”. The unit’s sensors take a “snapshot” of the local gravity around the unit before a flight. During travel, this baseline is periodically checked to make sure there are no major changes in the environment that would cause a catastrophic mass failure (brick wall appearing from nowhere). The percentage of VGL divergence from one worldline to another is a calculated guess by the three computers that control the unit based on its starting point. It is useless in describing characteristics of individual worldlines.
There is a bit of folklore about the first distortion driver who reaches a destination with a zero divergence. This would mean they had traveled on a spacelike trip to their own worldline of origin. This paradox is quite possible although highly unlikely. I wonder if anyone out there can take current string theory and make that one work on paper?
((You said 6 curled up dimensions. The current theory suggests that there should be at least 7 curled up dimensions.))
I may be mistaken but I thought it was pretty well established now that (N -10) was on track.