Do you read the entire sentence, before trying to parse the grammar?
For example, when reading "The man returned to his house was happy", you don't provisionally interpret "The man returned to his house" as meaningful?
I'm a native English speaker, living in a foreign country, so I spend most of my day working with a language I'm not completely fluent in, and I find I do the opposite-- I'm trying to put the meaning together word by word as the sentence unfolds, which makes reading things with long, Proustian sentences very difficult.
So to contrive your example, a fluent speaker would know both the transitive and intransitive uses of "returned" and, preferring the intransitive interpretation ("I returned home"), would reach your conclusion. But if a non-fluent speaker only knew -- or was stronger with -- the transitive version ("I returned the book"), they would arrive at the correct interpretation.
I hope that makes sense, it was a lot harder to explain than I anticipated!