Is it possible to get via CLI the commercial name (Lion, Mountain Lion, Mavericks, ...)
Well as you said it : it's a commercial name and it's barely present in the OS it self. It no real wonder, it has no meaning for devs (far less than a version or a build number). 

AFAIK It's mentioned in some help pages, but that's almost all.

So until someone would prove me wrong, there is no CLI for that (excluding curl stuff, which would imho not be a suitable option here).