Add the following additional row to the message list in the issue.item.html (inside the 'tal:block tal:repeat="msg context/messages/reverse"'):
<tr><td colspan="4"> <table class="files" tal:condition="msg/files"> <tr> <th i18n:translate="">File name</th> <th i18n:translate="">Type</th> <th i18n:translate="">Edit</th> </tr> <tr tal:repeat="file msg/files"> <td> <a tal:attributes="href file/download_url" tal:content="file/name">dld link</a> </td> <td tal:content="file/type" /> <td><a tal:condition="file/is_edit_ok" tal:attributes="href string:file${file/id}">edit</a> </td> </tr> </table> </td></tr>