I keep having the Cannot open source file "Filename.generated.h" error.

Intellisense errors (the squiggly red line) aren’t real errors, generally speaking when using Unreal. Intellisense has a terrible time parsing UE code (which is why so many people use Visual Assist instead).

Your build is failing because “UIceGirlStatics::FindLookAtAngel2D” is apparently defined twice.