Dogs (and sometimes rats) are trained to do search and rescue, so I'd counter propose something like lost-pet instead. ItsIt's less confusing, and more... laypersony.
community-faq is a bit of a special case of meta tag. ItsIt's meant for questions that are asked super often, and the goal is to build a canonical resource for similar questions. Quite a few sites have it, and itsit's one of those things that should be more, not less.
No strong opinions here.
It might be useful to consider in trying to merge - collars and harnesses are things that interface with pets. Leashes interface to humans. Folks often have strong preference with respect to all 3! I don't think leashes is the 'right' main synonym, but I can't think of a single simple englishEnglish language option that covers all 3.