Some might say Frank could have come in on a non-British ship and/or one not registered in the Atlantic Provinces but I think the killer was a London regular who was present around the time of the Whitechapel Murders and copied them, so he'd be in the Canadian/British Crew Records collection.
Frank Anderson was found in this record: Canada, Seafarers of the Atlantic Provinces, 1789-1935
Frank also wouldn't have taken the farmhand job unless he was discharged or deserted in New York. So any short layover-possibilities of several days in NY, for ships not registered in the Canadian Maritime Ports, around April 24, 1891 which would not be specifically recorded in the available crew records, but only in ship arrival and departure records in the journals and papers, would not count in my estimation. Desertions and discharges from non-British ships or British ships that only go between the Caribbean and NY might count if I didn't believe he was a London regular.
By comparison, Fiegebaum was on German ships and might not have been in London. LaBruckman, according to Conlon, was on National Lines passenger ships. Examples of merchant crew coming to New York on British shipping should well be findable like Frank Anderson.