A reranker fixes most of your misses but still prefers “safe for children over three” to “not safe for children under three”. What do you conclude?

A reranker is a better ranker, not a reasoner. On the course's data it ranked the right article first for 5 of 6 queries, but scored the reassuring toy article 4.66 against 3.89 for the one that answers.

So keep more than one candidate, instruct the generator to read carefully and answer only from the passages, and keep negation cases in the evaluation set.