Thank you both for your replies, much appreciated.
@Oswald : I’m afraid I don’t have access to earlier N7 installations because I am using a new machine where I installed N8 directly 
I tried creating a preset myself, though, and it was saved @ ~/Library/Preferences/Nuendo 8/Presets/KeyCommands This is the only preset present in the folder which is weird because there should be more like Logic or ProTools etc.
@Steve : thanks for sharing this, I checked all the places mentioned there and the only place where Key Commands where present is the path I mention above.