The /Web Framework Commons/config/alfresco/messages/common.properties (in the source tree) contains the labels for roles (e.g. roles.editor, roles.consumer, etc) update the locale specific versions of this file to change the labels in Share.
Yes, if your app is deployed, you'll find most of these labels in the file <TOMCAT>/share/WEB-INF/classes/alfresco/messages/common.properties. Or for other languages, there are files like common_fr.properties, common_de.properties etc.