Latest achievement displayed in bbpress author

Howdy all, lovely plugin. Really working well on my site.

I’m trying to modify bbpress to include the latest achievement somebody has earned in their author box to the side of their reply on the forums.

I’ve use the following code in other area’s of the site…
<?php echo get_the_post_thumbnail( dpa_get_user_last_unlocked( bp_displayed_user_id()), ‘thumbnail’); ?>

But I can’t find what file to edit and add code to in bbpress and which code to add?

Here’s a link to where I’m trying to get the latest achievement thumbnail:

http://gyazo.com/4b260721edf6659e2dff3600bdb27d33

Anyone have any experience doing something similar before? Any advice would be most appreciated.

https://wordpress.org/plugins/achievements/