Your importer is basing this on Foreign Supplier Verification Program (FSVP), which is a risk based preventative controls methodology per CFR Title 21 Part 117. So, what they ask for is what they have determined to be critical for a foreign supplier approval. You will have to ask the importer if 3rd party audits meet their approval requirements.
Certificates for export are commonly issued by the FDA for foreign governments, essentially stating that this specific commodity meets regulatory controls. If the FDA inspects your facility, I can only assume that this should be issued. However I do not believe (someone correct me if I'm wrong) this is based on a product and not its components.
If the FDA has an MOU with your countries regulatory body, and you have evidence of compliance then this should be sufficient for approval (IMO).
I have attached some FDA guidance documents:
FSMA-FSVP coverage flowchart - v4-.pdf 68.29KB
FDA Export Guidance for Industry.pdf 25.49KB