My Open University Diploma (German) was accepted as a B1 substitute at my Einbürgerung interview.
I took the original Diploma plus the accompanying course result letter from the Open University, along with certified (beglaubigt von einem amptlich vereidigten Übersetzer) copies and translations of both.
For anybody needing a B1 substitute for the Einbürgerung process, ensure Germanistik is on the translation, not Deutsch.
(British 'A' level may possibly be accepted.)
(I can highly recommend firstname.lastname@example.org for anybody needing English-German translations, certified or otherwise)