Have a look at this question. User is asking for clarification for why he didn't earn that badge. That user edited (re-tagged) this question which was inactive for more than 6 months. But he didn't earn the badge. Does tag edit count for Excavator badge?
If no, we need to mention it on List of all badges with full descriptions. If yes, Why didn't that user earn that badge? (other users who edited after him has already earned the badge.)