Yes, there shall be a process, but KPI might not be required. How?
When you combine sequence of "small" processes into one "bigger" process, let's call it "system process", you are not obliged to identify individual KPI for every "small" process. You identify KPI for "system process".
7.2.3 is about competence of internal auditors, but internal auditors are small part of organizational staff and we have to establish process, which has to ensure, that whole staff is competent and not only auditors. We have also trainers, product designers,
FMEA team members, control plan team members, persons with authority to release product and delivery, process setup staff, staff involved in statistical process control. All of these groups have to have individual KPI? Only auditors because they have own clause 7.2.3? Answer is "No". Put them all in one sack and monitor KPI for process ensuring competence requirements are fulfilled and that's all.
Just press CTRL+F and search IATF 16949 for "documented process". I've counted 15. 3 of them could be merged in 1 process for human resources management, including competence of whole staff, competence of internal auditors and employee motivation. It's up to organization how system processes are established. Some combine them, some not, but all 15 have to be found somewhere there.