Why Civil War casualty estimates can rise

Are revised estimates that raise American Civil War casualties plausible?

A higher figure is plausible because wounded soldiers who survived initially but died on the journey home could be missed in casualty accounting.

Casualty totals depend on which deaths the records capture. A soldier could survive the first days after a battle, be sent home, and die during the journey. The question is where that death appears in the accounting. Such cases make a higher revised total plausible.