Use the Diplomacy Dev Exe to locate errors in your install root dir e.g.
C:\Program Files\Stardock\Sins of a Solar Empire\Sins of a Solar Empire Diplomacy Dev.exe
GameInfo files are in Mods GameInfo folder e.g.
C:\Users\myfist0\AppData\Local\Ironclad Games\Sins of a Solar Empire\Mods-Diplomacy v1.011\My mod\GameInfo\BlaBlaBla.entity
If you have any other mods you can check them for directory structure. If you are new to modding, the SoaSE Weebly has lots of good info.