XXXXX had # (small #) of corrective actions for the year. Both had shallow RCA performed and did not find true root cause.
It seems to me that you've agreed with the auditor. You seem to agree that your system failed to determine root causes so they could be eliminated or mitigated.
Not being able to retrieve records of the actions taken to determine root causes is a failure of your filing and archiving process (see 4.2.4).
You may need to invest in Ford Global 8D training so you have a well-defined methodology. You can Google for some excellent forms a free elearning is available in the methodology.
As to root causes avoid blaming any individuals. Your management system seem to lack a process for succession planning and take a look at your processes for bringing the necessary competences into your organization. You may find recruiting and/or training are weak.
While your at it work with your colleagues to develop a plan for revitalizing your process-based management system so it help employees to meet requirements.
Good luck,
John