bbPress.org

Looks like the forum ate your code but to display the forum name when you only have the id, you can use the built in bbpress functions

echo get_forum_name($result->forum_id);

or

echo "Posted by $result->topic_poster_name in ".get_forum_name($result->forum_id);

or

echo "Posted by <a href='".bb_get_profile_link($result->topic_poster)."'>$result->topic_poster_name</a>

in <a href='".get_forum_link($result->forum_id);."'>".get_forum_name($result->forum_id)."</a>";