Internally, I would not change it but looks like its controlled by the following resource bundle. You can override, edit and rebuild this to do "text tailoring" to change what is displayed to the user:
Windchill/src/wt/workflow/work/WfAssignmentStateRB.rbInfo
# Entry Contents
ACCEPTED.value=Accepted
ACCEPTED.shortDescription=accepted state
ACCEPTED.order=20
COMPLETED.value=Completed
COMPLETED.shortDescription=completed state
COMPLETED.order=30
POTENTIAL.value=Potential
POTENTIAL.shortDescription=awaiting acceptance state
POTENTIAL.order=10
POTENTIAL.defaultValue=true
You should be able to change .value to display something else. Follow standard steps for rebuilding resource bundles.
https://www.ptc.com/en/support/article/CS30472?source=search
