The EFATO was not a TOTAL engine failure. Just sufficient power reduction (not even enough to maintain S & L) to leave no choice but to forced land , and quick.
The majority of engine failures aren't complete engine failures or catastophic power loss. Partial power loss is indeed an engine failure, regardless of whether it requires a forced landing, or not.
A rough running engine...you just had an engine failure, whether you realize it, or not.