But my Greek studies took place 20 years ago so I do wonder what you mean by eta and eta + nu words? Are these different subtypes of the third declension?
Also, for example, tau+iota is either an interrogative or an indefinite pronoun, and it is the accent which tells you which without having to scan further through the sentence.
Well sure, there are minimal pairs, but most of the time it’s immediately clear from the context, and we have to keep in mind that the accents were added much later by modern philologists, so they have de facto been deduced from the context.
But sure, there goldilocks zone where it’s not obvious to the lay reader, but the scholars are pretty certain what it should say, and then it helps. I wouldn’t say it’s a major struggle when reading Greek though.