Is it recommended to translate values of response payload objects in MuleSoft integration layer based on mapping between source and recipient system codes?

I want an opinion regarding a situation. We have a vendor having a SaaS product which calls our API via MuleSoft AnyPoint platform that returns demographic values (e.g., Country of birth, Language) in response payload based on our source system codes. The vendor wants translation of the values based on mapping with their identifiers and to be maintained at the Mule integration layer. We pointed limitations and risks associated with performing the mapping within MuleSoft, primarily ongoing maintenance and support responsibilities. We recommended translation to be performed by the vendor. Is there any other option? How can it be done? 

#MuleSoft Anypoint Platform