per feedback in demo

spiffworkflow-frontend/src/index.css

@@ -29,6 +29,12 @@
   border-color: none;
 }
 
+/* make this a little less prominent so the actual human beings completing tasks stand out */
+.system-user-log-entry {
+  color: #B0B0B0;
+  font-style: italic;
+}
+
 h1 {
   font-weight: 400;
   font-size: 28px;

spiffworkflow-frontend/src/routes/ProcessInstanceLogList.tsx

@@ -80,7 +80,11 @@ export default function ProcessInstanceLogList({ variant }: OwnProps) {
         <>
           <td>{row.bpmn_task_type}</td>
           <td>{row.message}</td>
-          <td>{row.username}</td>
+          <td>
+            {row.username || (
+              <span className="system-user-log-entry">system</span>
+            )}
+          </td>
         </>
       );
     }