We don't have synonyms for tracker yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are cracker, trucker and tracer.
(n) :
one who, or that which, tracks or pursues, as a man or dog that follows game; in the organ, a light strip of wood connecting (in path) a key and a pallet, to communicate motion by pulling
(n) :
one who, or that which, tracks or pursues, as a man or dog that follows game; in the organ, a light strip of wood connecting (in path) a key and a pallet, to communicate motion by pulling