I have your documents for the internal audit report and the checklist, on the internal report is it acceptable to state that everything was implemented correctly and there was no finding for improvement?
Although it is acceptable, it is highly unusual that the results of an internal audit point out that everything was implemented correctly AND there are no opportunities for improvement (a certification auditor would certainly check a such report in more detail).
If everything is consistently being performed as planned, then the next step in maturity could be an opportunity to be considered. For example:
Efficiency could be increased
Productivity could be increased
Rework could be decreased
Costs could be decreased
This article will provide you with further explanation about improving processes maturity: