We don't have synonyms for factfinder yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are faultfinder, fact finder and fact-finder.
(n) :
(law) In a legal proceeding, the person or persons given the task of weighing all evidence presented and determining the facts of the case in light of that evidence; the jury, or where there is no jury, the judge.
(n) :
(law) In a legal proceeding, the person or persons given the task of weighing all evidence presented and determining the facts of the case in light of that evidence; the jury, or where there is no jury, the judge.