I would guess that
Salome Asenath and
Susannah might indicate this family were members of a Protestant group other than Church of England, which also might be a reason for why you can't find a baptismal record. Perhaps they belonged to a group which did not believe in infant baptism.
It would be difficult to figure out why they named a daughter
Joseph unless you can find something written about this by a family member. Perhaps she was born on her parents' anniversary or her father's birthday. I have a first cousin named
Stuart Ann because she was born on her father
Stuart's birthday.