Hmm, this sounds a bit complicated as bbpress replies are not technically ‘comments’, they are a separate post type, the same as topics, that are simply connected to their parent topic (as far as I know anyway).
The first thing I would try is to copy the code that displays comments on a regular post, and add this to the template that displays my topics. That way, if comments are attached to the topic, they will display when viewing the topic on the front end.
You want to find the template ‘content-single-topic.php’
This should be at wp-content/themes/your-theme/bbpress/
(If it’s not, read up on theming here: https://codex.bbpress.org/theme-compatibility/)
Then add this code somewhere in that file:
<?php wp_list_comments(); ?>
If no comments appear when you view a topic, then I would check in my mysql database to see how the comments are being saved – perhaps they are saving to the database but without being assigned to a specific post (topic). You may need to enable comments for the ‘topic’ post type.
I hope that helps, it is a bit complicated as I said.
the recent comments widget is just displaying any comment from your facebook page most likey,
not that is has any comments on a particular topic from bbPress, but that you just shared a topic as a “status update” and people are commenting on that “status update”.
@herculaas if you want this kind of functionality , which would be pretty difficult to create you should hire a developer and post a job at http://jobs.wordpress.net/