File src/add-button.js uses in line 40 a compound text string which is difficult to translate.

To avoid a difference in formal and informal German, the best translation would be "{post_type} hinzufügen".

Currently the button uses a compound of "Add new" (Erstellen) and Posttype. "Erstellen Seite" and "Seite Erstellen" are both gramatically wrong; the first sounds odd, the second has an incorrect capital "E".

Providing a text string where just the post type is replaced would make it easier to translate: %s hinzufügen (as translation for Add new %s) would fit to the typical wording in WordPress.