post type items to back-end wp_nav_menu

Just curious where to start,

I found already how you can add a Post Type to the wp menu option (back-end) but how can you control what is taken from that post type to show inside a menu.

By default when you add a Post Type to this menu option it will take the title + make a link of the Post Type but what if you want to add something to this info.

I’m looking at this because I would like to make the easiest bbPress forum menu in the world and for grouping single forums together.
Right now, there is a menu option but it only shows the forum title I would like to add topic counts + post counts to this.

Does anybody know where to start or maybe you know a plugin who does something similar so I can look at the code and go from there..

Thanks.