Ok, I understand.
You have more than one field.
Try those xpath:
<entry key="Status_Flag" value="ns1:Worker_Data/ns1:Integration_Field_Override_Data[ns1:Field_Reference[ns1:ID[@ns1:type='Integration_Document_Field_Name']='Status_Flag_New']]"/>
<entry key="Status_Flag" value="ns1:Worker_Data/ns1:Integration_Field_Override_Data[ns1:Field_Reference[ns1:ID[@ns1:type='Integration_Document_Field_Name']='Status_Flag_New']]/ns1:Value"/>
I am not sure with Value at end or without, try both