Yes - you are quite right the family who arrived in 1838 are a different Kalleske family and I'm fairly certain that the death record/s that Judith found relate to this family.
Graeme Moad's listing was quite helpful but it seems that he and I have got to the same point with Johann Georg Kalleske. I remember (as a ten year old boy) my granny talking one day about the Kalleske/Jaeger family connection and Johanne Eleonore Franke - but I don't recall!
There seems to be an absence of documentary evidence - perhaps he died at sea, perhaps he deserted his wife and children and she remarried, perhaps he died in SA and his death was not recorded?
Family arrival in Port Adelaide 3 September 1855
Remarriage to Christian Jaeger 23 April 1856 in Tanunda - she must have been several months pregant at the time
Birth of Maria Dorothea 6 Dec 1856.