The scripts do not really check anything that would make the footprint or symbol safer to use. They mainly check stuff that is only important for having a consistent library.
The things that are really important need to be hand checked (this is the main work that library maintainers do.) So the pin number, pin name and pin type stuff still needs to be compared to the datasheet. And for footprints a dimension check is also in order (For that i have a tutorial for my workflow here on the forum: Tutorial: How to check footprint correctness?)
For a lot of footprints we have quite powerful generator scripts that make it easier to get it right. (for most standard IC packages there is one that uses IPC equations and constants to arrive at a footprint from package dimensions) They are found here: https://github.com/pointhi/kicad-footprint-generator