I am using a question as example, but I am not suggesting that the question needs to be re-opened. This question is about what needs to be done, if something needs to be done, after the new question is closed as duplicate of a question tagged faq.
What happens if I delete a question with a bounty? has been closed as duplicate of How does the bounty system work? Effectively what asked has been already answered in that faq question, even though the used sentences ("Bounty questions cannot be closed. However, diamond moderators can refund bounties, which would then allow it to be closed, migrated, or deleted.") could leave some doubts about the fact they apply to the specific question. The first sentence just make reference to questions with bounty, which cannot be closed, while the second sentence says that once the bounty is refunded, the question can be migrated, deleted, or closed; from that, I assume that (without the bounty being refunded) the question cannot be migrated, deleted, or closed (even if the first sentence talks of closing a question with a bounty).
When are there questions that make you think the answers for a question tagged faq should be rephrased to be clearer, or be expanded to include a specific case, should the faq answers be edited, or left as they are? In which cases should the answers be edited? Do we decide basing on the number of new questions asked about the same topic?