You could try highlighting it to the PC, but you’ll probably find they already know and either don’t have the interest, expertise or resources to update.
You could try the Monitoring officer, bit of a stretch, but it could be preventing access to information to which you would be entitled - but unlikely to be CoC since the ‘complaint’ would be against the PC rather than a named individual - ergo, not MO CoC territory.
You could try the auditor (IA and / or EA) but that’s fairly nugatory too.
I’d suggest your best bet, depending upon what it is that is not being updated, would be to highlight the ICO model publication scheme to the PC and, if the elements you believe to be unpublished or outdated fall within the terms of the ICO MPS, forward your complaint to the ICO if PC refuse to engage.
ICO can DIRECT compliance and fine for failure if necessary.