The flight attendants do (or should) make notes when a passenger points out a non-working item such as a light, loose trim, seat back that won't stay up, won't recline, etc.

If the item is a safety issue it can put the seat out of use if the plane is not going to a station with mechanical personnel. If it is a minor item such as a light then it's noted for the overnight. Some items can be "no go" items and those cause delays if they have to contact contract maintenance in a non-maintenance station. (that also can be a reason for an aircraft swap).

Also the aircraft are checked on a regular basis and these items can be found then as well (if not noticed or note on a prior flight).

When a passenger tells me of a problem, unless it's a safety issue I don't stop what I'm doing to go report it to the captain. But note it for when we are passing through a mechanical base.

hth