I've found an edge case in Text::MultiMarkdown (1.000034, latest from CPAN) regarding wikilinks this time. Line 318 of MultiMarkdown.pm reads:
$text = $self->_UnescapeWikiWords($text);
But this implies that it will perform unescaping even when use_wikilinks is not set. It seems to me like this should be changed to something like:
$text = $self->_UnescapeWikiWords($text) if ($self->_UseWikiLinks());
For slightly more consistent behaviour.