A quick hack to make that work: in assets/snippets/wayfinder/wayfinder.inc.php change line 182 from
$phArray = array($useSub,$useClass,$classNames,$resource['link'],htmlentities($resource['title'], ENT_COMPAT, $charset),htmlentities($resource['linktext'], ENT_COMPAT, $charset),$useId,$resource['alias'],$resource['link_attributes'],$resource['id'],htmlentities($resource['introtext'], ENT_COMPAT, $charset),htmlentities($resource['description'], ENT_COMPAT, $charset),$numChildren);
to
$phArray = array($useSub,$useClass,$classNames,$resource['link'],htmlentities($resource['title'], ENT_COMPAT, $charset),$resource['linktext'],$useId,$resource['alias'],$resource['link_attributes'],$resource['id'],htmlentities($resource['introtext'], ENT_COMPAT, $charset),htmlentities($resource['description'], ENT_COMPAT, $charset),$numChildren);
That keeps any special characters in content of the Menu Title field (linktext) from getting encoded with htmlentities(). So <img> won't become <img>