You could check out this tutorial. It shows a lot of tips and tricks of how to work efficiently with kicads footprint editor: Tutorial: How to make a footprint in KiCad 5.1.x (From scratch)?
For scripting footprints there is also the stand alone scripting stuff that is used to generate a large part of the official library. This can be found here: https://github.com/pointhi/kicad-footprint-generator