Intellisense sucks, unfortunately - and it won’t find half the things you need. Your best bet is to just look at the parent header file to see what functions are available for you to override (I’d also recommend investing in Visual Assist X - it’s a better intellisense and more, and actually works).
Nothing you can do about the generated.h file warning, but it’s not a problem anyway (it won’t stop you compiling - and those headers don’t exist until compile time anyway).