What sets CPIMS+ workflow statuses?
Workflow statuses are usually triggered when a user performs an action on a case, or fills out a specific field. In addition, certain workflow statuses may only appear if an implementation’s configuration is set to use that workflow status.
This document outlines which actions, fields, and configuration settings control workflow statuses: https://docs.google.com/spreadsheets/d/1XkLRkqIRPc__IuZLqpyAll0rzW40U3QHHV9RGFseQR4/edit?usp=sharing
I hope this answers your question!