You don't need an auditor to sign off on the financials of a cc. However, it is always a good idea to at least get an accountant to run over the financials before you present them anywhere.

The members should sign off (take responsibility for the accuracy of) the financials. Technically the role of the accounting officer is to ensure that the financials and various returns are completed and submitted. Practically, the accounting officer is a point of contact.

BTW any member of the cc can be the accounting officer. It doesn't have to be an accountant. It's not a skill - it's a responsibility