For example, a friend of mine posted a picture of a book series on Facebook and the start of his caption was "Read all 13!" I initially interpretted this as an imperative sentence ([ɹid] all 13), but after reading the entire capture, I figured out that it was actually a declarative sentence about what he had done ([ɹɛd] all 13). Is there a term for this phenomenon? I dub it "homonym confusion" if it lacks a name!
'Homonym' usually means same spelling (=homograph) and same pronunciation (=homophone) so what you describe would be better referred to as 'homograph confusion'. But in my experience what you describe is usually called 'orthographic ambiguity' in the linguistic literature.