In my situation, I was unable to use the API directly, because it doesn't integrate with the language i'm working in (which is called Business Rules). There is no way to call a general API like that, though its easy to run a command line program. Thats why i looked at GoogleCL in the first place.
So, in the end, my only option for using the API directly, would be to write my own GoogleCL that properly handles events. Unfortunately, for you, I didn't, and the googlecl they offer won't give you the event ID at all.
I ended up solving my problem by saving not the event ID, but saving every detail of the event, into my database, whenever I use GoogleCL to add an event to the google calendar. Then, if I need to delete that event later, I can use every single detail of the event together to get a description of the event that GoogleCL will accept, that only identifies one single event ever.
Gabriel