Hi Ian
The database that comes with RB is pretty good, but the basic data will always be out of date. Aircraft are being built, bought, sold, leased, re-registered and scrapped all the time. It's a heck of a job to keep up with it all. It's also true that Europe and North America are better updated than the rest of the world as enthusiasts are on the lookout, and can observe and share their information more freely than in other places.
There is no such thing as a definitive database of all the world's aircraft - it is changing by the minute.
AirNav are looking at ways of improving the updating of the database, but it will always depend on Internet access. Without that, you would have to update the database manually - an impossible task!
There may be RB users who keep their NavData database well up to date who would be happy to share their database with others, and you could download that whenever you do get online. I'm not a particularly enthusiastic database updater, but there are others who are!
I know that's not a solution, but I hope it's a reasonable explanation!
Rod