Status is the query's overall honesty signal: ok every consulted leg answered. partial at least one leg failed; Hits holds the survivors' results. unavailable every consulted leg failed; Hits is empty AND that is stated.
TookMS is the whole query's wall time in milliseconds — every leg it consulted, plus fusion and paging. Each leg's own share is in Backends[].TookMS; the legs run in sequence, so this is at least their sum.