v1.0.342.0 released. See post #1
This version removed the hard-coded reading of some items in the ArtToolInfo:ExtendedData. Now the file tells it what to read based on the pointers. As a result of this the Undersea.gr2 file can now be read
There is currently only one file I've found that it can't open still - \data\Library\ShipParts\guns_radars_01.gr2. Looking into why currently....