Hello, I'm searching the game files to see what I can get out of it and I have come up with some great finds for my purposes.
Will post some info I found on the game periodically, when it seems interesting. It might be of use to those updating the wiki, so you can post your finds too if you'd like. Mine so far:
-The Galactic Senate image has seats for 416 civs. I counted one segment that had 104 ones, so it seems to have 4 of them and it should be symmetrical, since they usually are, thus multiplied by 4=416. IMO this should be the theoretical upper limit for simultaneous galacticivs if they ever manage to add such a possibility to the GCIV game.
-There is a "GalCiv3FlavorTextEditor" executable somewhere in the files(not sure if I should tell you where in case someone fiddles with it in a way they shouldn't). I copied it elsewhere and run it and it creates 2 files locally: "CustomFlavorTextTemplate.xml" and "GalCiv3FlavorTextEditor.prefs". If this is used, it should probably be renamed either "GalCiv4FlavorTextEditor" or "GalCivFlavorTextEditor". It might be a case that it remained a remant or residue of the previous game which possibly was used as the skeleton for the initial development of GCIV.
-In the logos folder, the game asks the user to put in there 512x512 pixel sized images but I found that all stardock logos there, where 128x2 and 256x2 ones. I already resized some of mine, having the original files they derived of, but since some I'm not sure if I have the files I used for each one(and upscalers don't do a great work without AI filters on, which you might not be able to afford), it seems 256 versions and even 128 versions of older games still work. But for better results, try to make them with transparent background(Though I have some with normal backrounds and they look awesome as well).
-I can't seem to find a dedicated star folder with all the stars proportions and images. I wonder if it seems they're all basically 512 images for each star I did find, or they're hidden in some format(like dds).
-It seems all AGPT available leaders pics for custom purposes are stored in the machine. There are about 1200 of them.(if more exist, I'm assuming the ones that where browsed are the ones saved). If some were used for civs, their leader pic - if one exists(but should be easy to make in almost any graphic editor if there isn't one, they're so advanced now) - is also saved.