I can only assume that the mapdefs from whatever was the version of GalCiv when Crusade split off (1.9? 2.0?) is in here.
The MapSizeDefs in Crusade are the ones from 1.9, not the ones from 2.0. Changing them to the ones in 2.0 should stop most of the complaints about the sizes of the galaxies.
For those who are more insane than the usual insane, I have something to report. Larsenex asked about sizes larger than Insane in this post. I did some testing then and found that the game crashed if the value for MapSizeDef for Insane was increased by 1 or more above the value of 380. Today, Brad made a comment somewhere, I think the Steam forums, that it is possible to have larger map sizes in Crusade than those that exist. I decided to find out if Insane could be made larger, so I made a mod and have been increasing the size of Insane maps to see how large I can go before the game crashes. I have increased the value of MapSizeDef to 500 so far (31.5% increase) without a crash during galaxy generation.
I tried more sizes, all the way to 1140, without a crash. However, the galaxies looked to similar, so I tried zooming out and seeing how the bottom edge looked against the UI on the screen. They all seemed to be the same size the galaxy with a value of 380. I need to do some work to see if the galaxy sizes are actually increasing with values larger than 380.