I admit I don't understand why the zpBase theme hides the headline but I assume that is a CSS issue? As far as I remember the theme supports custom CSS via the backend so you could probably force displaying it with `ul#relateditems li h4 { display: block !important; }`.
You can even address the individual item type as the`li` will have the class of it (albums, images, news, pages).
if you wish another headline structure you will have to create a custom version of `printRelatedItems()`. The headlines follow the though that site name = h1, item = h2 so the related items start with h3 for the "section" headline and h4 for the entries itself.