The OAG expect to be able to find out how much a Crown entity or Council has spent resolving employment disputes, but generally does not need to know the details of each dispute. Here's the link to the Office of the Controller and Auditor General's relevant function: https://oag.parliament.nz/good-practice/sensitive-expenditure/the-basics .
We know of a few ERA and Employment Court proceedings that may be of interest to the AOG - not the defence of Personal Grievance claims but actual SLAPP proceedings brought at taxpayer / ratepayer expense.