Currently the "descriptive title" of the Popups extension is Page Previews ( in German this was translated to Seitenvorschaubilder ).
Since the extension itself became more general with the addition of Reference Previews the descriptive title probably should also reflect that.
This probably only makes sense, when we decide on going out of beta with this. Currently the feature is completely hidden behind the beta switch.
 e.g. found on https://en.wikipedia.org/wiki/Special:Version in the list of installed extensions