Looking at the way the code is structured, it is sectioned off into different title types (categories).
Most of the logic used to display each section uses strings, like the Fame/Karma titles.
With that in mind, you could add a new section by copy/pasting all the logical code for the Fame/Karma section, and adapt it to use your Achievement's titles. Add a new TitleType for your section too.
You will likely need to modify the gump's layout to accommodate the extra section too.