I had this problem, too.
I’ve started to sleuth it out and here’s what I’ve found so far.
The creators of the theme have a demo of it here:
https://sprachkonstrukt2.deyhle-webdesign.com/
If you look in their page source, you can see the buttons are actually an unordered list. The one on their demo looks like this:
<ul id="menu-social" class="socialbuttons"><li id="menu-item-760" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-760"><a title="RSS" href="https://sprachkonstrukt2.deyhle-webdesign.com/feed">RSS</a></li>
<li id="menu-item-759" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-759"><a title="Twitter" href="https://twitter.com/iruben">Twitter</a></li>
<li id="menu-item-758" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-758"><a title="Facebook" href="https://www.facebook.com/sprachkonstrukt">Facebook</a></li>
<li id="menu-item-802" class="menu-item menu-item-type-custom menu-item-object-custom menu-item-802"><a title="Google" href="https://plus.google.com/114960565817170980570/posts">Google+</a></li>
</ul>
The titles are all coded in your CSS with their associated attributes, which you can access via the Editor. It’s a very clever thing, but I have yet to make it work for me.
