classic/html/issue.search.html, line 208 and following:

 <td colspan="4" class="help" i18n:translate="">
   *: The "all text" field will look in message bodies
and issue titles<br>
   <span
tal:condition="python:request.user.hasPermission('Edit',
'query')">
   **: If you supply a name, the query will be saved
off and available as a
       link in the sidebar
   </span>
 </td>

The <span tal:condition...> in line 210 breaks the
translation of the help texts; IMHO, there is no
alternative to splitting the two help texts.

In my issue.search.html, it looks like this:

<tr>
  <th>*:</th>
  <td colspan="4" i18n:translate="">The "all text"
field will look in message bodies and issue titles</td>
</tr>
<tr
tal:condition="python:request.user.hasPermission('Edit',
'query')">
  <th>**:</th>
  <td colspan="4" i18n:translate="">If you supply a
name, the query will be saved off and available as a
link in the sidebar</td>
</tr>

(with appropriate translations)