“So you're saying that sometimes time itself interferes in order to keep certain people alive?”
This is a very good point. Conan Doyle brought Holmes back after he 'killed' him at the battle with Moriarty. (I reckon he has something in common with JKR, in this regard. Though JKR was more bloodthirsty with *her* characters.).
That said, I had absolutely no idea what was going on, story-wise, but the poem was an excellent touch, as is the point about Snape translating it into English easily, even as Harry was reading the Latin. I would know. Translations are hard to do, even when sitting there and thinking about them.