请教PJiang等高手 I485RFE 问题 - Translator's Certification

I got I485 RFE as follows: "A review of the service record found a birth certificate from your country of birth and the English translation of that document. However, there was not a translator's statement attesting to their competency to perform the translation and that the translation is accurate."

I was asked to provide the document again and provide a translator's certification.

My question is:
1. Will USCIS accept my lawyer's affidavit? (My lawyer offered to provide an affidavit for the translation)
2. Or should I use a certified translation company?

Thank you very much.