[itsme]

In my case I display source type all the time in the caption to differentiate several versions of the same song that often have the same title. I ignore the default source types that come with MobileSheets and defined my own. Some show the file format of the current file like PRO, JPG, PNG or the file format from which the PDF has been exported like MUS, ABC or MSCZ. Some are abbreviations that tell something like "layout" e.g. LS for leadsheets or No(pi) for piano scores. Some tell the language of the lyrics like Tx-de or Tx-en. Not completely consistent but it works fine for me.

To make a long story short: I think "Typen" is not too bad. The keyword SOURCE_TYPES should stay untouched. But I recommend to make also the English UI consistent: keep "Source Types" as tab title and rename the buttons in both format dialogs from "Sources" to "Source Types".