The recommended translation for 'tiny hairy faces seemed worried' is 'de minuscules visages hirsutes avaient l'air inquiet' - inquiet agreeing with air rather than the subject visages.
Is it not also an option that it agree with visages?
I am looking in Larousse which says that the adjective following air agrees with the subject of the sentence if that subject is a thing and, often, with the subject if it is a person ('Elle a l'air sérieuse').