To change the translations?
Download the de_DE.po
file.
To amend the translations:
1) Download POEdit https://poedit.net/
2) Search through your strings and amend the translations. Save your file.
3) Fuzzy strings, marked in yellow will need to be un-ticked: Edit => mark as fuzzy
4) When finished, click File => Compile to MO.
5) Upload your new language files BOTH de_DE.po and de_DE.mo to the folder cardinal/languages/
Thanks,
David.