As a non technical person, who is about to fly an 80 ton vehicle for extended distances, local backups of WiFi dependent data is not likely to be a major concern.
Especially if (a) it’s not part of your extensive checklists, which would reasonably be expected to be included if it was important, and (b) you’ve lost WiFi in other planes before without losing your flight plan.
They were in cruise, which means the flight plan was already set and can be viewed on the MCDU. Sure they lost a fancy map on the ipad but that doesn't mean they suddenly don't know where to go.
