Nutty
Deity
I based my font icon observation on Firaxis' uses in the IconFontTextures table:Before I edited out the pathnames, I checked the atlas-defining code in other mods which added resources, but which didn't cause any problems on my computer. All those mods showed the same syntax: keep the .dds extensions, exclude the pathnames.
IconFontTexture='ICON_FONT_TEXTURE_DEFAULT', IconFontTextureFile='FontIcons'
IconFontTexture='ICON_FONT_TEXTURE_EXPANSION2', IconFontTextureFile='FontIcons_Expansion2'
EDIT: I think you're talking about IconTextureAtlases, which uses the .dds extension. Different table.
Good luck!