The python code is an implementation of a program that uses the Coinbase API to make trades, fetch market data, etc.
In my day, we'd call that a Program, Library or an SDK. Definitely wouldn't call that an "Unofficial API".
When I think of "Unofficial API", I think of an API that wasn't intended for public use and is undocumented and supported by the company. Like the Pandora API some music players have reversed... or the Pokemon GO API people are talking about in this very thread.
Coinbase released, documented and supports their API. Anything that uses that API to do things is just a program, or library.