Trove of course solves all mysteries (nearly). What did happen was that a ship called the Mariner arrived at Hobart Town in 1851 and a couple of passengers got off. This and their names were reported in a number of newspapers (a slow news day). It was also mentioned that 393 (numbers varied) “Chinese coolies” were also on the ship. Some of the reports were truncated and it would be easy to get the impression from these that everyone got off at Hobart Town.
This one makes it clear:
CHINESE EMIGRANTS. – The Ship Mariner, 683 tons, arrived in harbour yesterday from Macao. She is bound for Lima, South America, and has 393, coolies on board engaged as servants in Lima. The Mariner has put into this harbour to obtain supplies of water and provisions. Four of the coolies died on board from a species of cholera. The Moreton Bay Courier, 24 May 1851, p.4.
This is a problem with non-contextual history. From the context of Tasmanian and Australian history in general this number of Chinese people in Tasmania at that time would certainly have appeared elsewhere in the history. So the account in The Australian People (and repeated in at least one website) is inherently implausible and always warranted further investigation.