The following text: (http://php.net/manual/en/book.gettext.php)[[ URL | name ]] renders quite wrongly:

(http://php.net/manual/en/book.gettext.php)name

(pre-fix: (name" target="_blank">http://php.net/manual/en/book.gettext.php)name )

<p>(
  <a href="http://php.net/manual/en/book.gettext.php)&lt;a href=" w="" url="" "="" class="phriction-link">name</a>" target="_blank"&gt;http://php.net/manual/en/book.gettext.php)
  <a href="/w/url/" class="phriction-link">name</a>
</p>

This: (http://php.net/manual/en/book.gettext.php) [[ URL | name ]] renders just fine:
(http://php.net/manual/en/book.gettext.php) name

Note the space between the link-in-parens and the remarkup link brackets.

Accidentally discovered this in Legalpad but it's happening here in the Maniphest preview too so I imagine it's a deeper issue.