As far as I know there is no 'central' GPS database. Items displayed by the GPS are defined in the AP######.bgl files (..\Scenery\
\scenery\AP######.bgl). Each file defines airports, navaids, waypoints, etc., and
approaches within a geographic area.
'Scruffyduck' has released ADE9X-RC1. I see that, like ADE (for FSX only), ADE9X (for FS9 and FSX) has the 'Approach Mode' approach editor available in FS9 mode. Maybe this is just the tool you're looking for.
At that time [1909] the chief engineer was almost always the chief test pilot as well. That had the fortunate result of eliminating poor engineering early in aviation.