More identity key -> safety numbers changes

_locales/en/messages.json

@@ -37,13 +37,13 @@
       "description": "Header for a key change dialog"
     },
     "identityChanged": {
-      "message": "This contact is using a new Signal identity. This could either mean that someone is trying to intercept your communication, or this contact simply re-installed Signal. You may wish to verify their new identity key below."
+      "message": "This contact's safety numbers have changed. This could either mean that someone is trying to intercept your communication, or this contact simply re-installed Signal. You may wish to verify their new safety numbers below."
     },
     "outgoingKeyConflict": {
-      "message": "This contact's identity key has changed. Click to process and display."
+      "message": "This contact's safety numbers have changed. Click to process and display."
     },
     "incomingKeyConflict": {
-      "message": "Received message with unknown identity key. Click to process and display."
+      "message": "Received message with new safety numbers. Click to process and display."
     },
     "incomingError": {
       "message": "Error handling incoming message."