There are lots of possibly-related bugs here and they're all related to internal wikilinks within tables and a certain lack of whitespace, so I'll just list examples (copy and paste this into a page):
!!!||((foo))|text||
||((foo))|text||
works fine
!!!||((foo))|((bar))||
||((foo))|((bar))||
<td class="wikicell">foo</td><td class="wikicell">bar<a href="tiki-editpage.php?page=foo%FF298432%FFbar" title="Create page: foo%FF298432%FFbar" class="wiki wikinew">?</a></td>
!!!||((foo t))|((bar t))||
||((foo t))|((bar t))||
same problem as ||((foo))|((bar))||
!!!||((foo))|((bar|baz))||
||((foo))|((bar|baz))||
<td class="wikicell" colspan="2">baz<a href="tiki-editpage.php?page=foo%FF298432%FFbar" title="Create page: foo%FF298432%FFbar" class="wiki wikinew">?</a></td>
!!!||((foo t))|((bar t|baz t))||
||((foo t))|((bar t|baz t))||
same problem as ||((foo))|((bar|baz))||
!!!||((foo|boo))|((bar|baz))||
||((foo|boo))|((bar|baz))||
<td class="wikicell">boo</td><td class="wikicell" colspan="3">bar<a href="tiki-editpage.php?page=foo" title="Create page: foo" class="wiki wikinew">?</a></td>
!!!||((foo t|boo t))|((bar t|baz t))||
||((foo t|boo t))|((bar t|baz t))||
same problem as ||((foo|boo))|((bar|baz))||
!!!||text|((bar|baz))||
||text|((bar|baz))||
works fine
!!!||text|((foo))|((bar|baz))||
||text|((foo))|((bar|baz))||
same problem as ||((foo))|((bar|baz)||
!!!||text|((foo))|((bar|baz))||
||text|((foo t))|((bar t|baz t))||
same problem as ||((foo))|((bar|baz)||
!!!||text|((foo))|nospace|((bar|baz))||
||text|((foo))|nospace|((bar|baz))||
nospace disappeared! <td class="wikicell">text</td><td class="wikicell" colspan="3">baz<a href="tiki-editpage.php?page=foo%FF290656%FFbar" title="Create page: foo%FF290656%FFbar" class="wiki wikinew">?</a></td>
!!!||text|((foo t))|nospace|((bar t|baz t))||
||text|((foo t))|nospace|((bar t|baz t))||
same problem as ||text|((foo))|nospace|((bar|baz))||
!!!||text|((foo|boo))|nospace|((bar|baz))||
||text|((foo|boo))|nospace|((bar|baz))||
same problem as ||((foo|boo))|((bar|baz))||
!!!||text|((foo t|boo t))|nospace|((bar t|baz t))||
||text|((foo t|boo t))|nospace|((bar t|baz t))||
same problem as ||((foo|boo))|((bar|baz))||
!!!||text|((foo))|has space|((bar|baz))||
||text|((foo))|has space|((bar|baz))||
works fine
!!!||text|((foo|boo))|has space|((bar|baz))||
||text|((foo|boo))|has space|((bar|baz))||
works fine
I think the code responsible for this just needs a total rewrite.