Look, I’m fine with certain minor things in the Star Wars universe not making complete logical sense. I mean, it seems like it’d be a lot easier if astromech droids just spoke English (Arabesh? whatever…) rather than bleeps and whistles, but who cares?

The movie straight up tells us that the resistance does not have a map of that region of space, so the fragment from Lor San Tekka is meaningless without context. Then R2 spontaneously reactivates and reveals he has the full map minus that one fragment. It seems to me like something that needs an explanation.

Either someone (possibly Luke, possibly someone else) knew where Luke was going and put an incomplete version of the map in R2 (why?). Or someone tracked Luke’s journey, created the map, and put it in R2 without telling anyone else in the Resistance (again, why?).