The “Fields” tab content is defined in: $:/core/ui/TiddlerFieldTemplate, which contains:
<tr class="tc-view-field">
<td class="tc-view-field-name">
<$text text=<<listItem>>/>
</td>
<td class="tc-view-field-value">
<$view field=<<listItem>>/>
</td>
</tr>
If you change <$view field=<<listItem>>/>
to <$transclude field=<<listItem>>/>
then the display of the field contents will be “wikified”.
This will cause any WikiWords contained in the field values to be rendered as tiddler links,
and any text starting with “http://”, “https://”, etc. will be rendered as external links.
enjoy,
-e