If the school does what it should with regard to race, the existence of a written policy is of minimal importance. A challenge would surely only come if your practice was bad.
I agree and yet we come across too many "ticky box" administrators/auditors of one sort or another - I used to have a running 'discussion' with the regulators of my former industry who seemed more interested in the process than the outcomes (even threatened us with enforcement action once because we did not follow the procedure even though had we done so the outcome would have been worse for our customers!).
There seems to be a common development route with regulators (of which I have considerable experience - honestly!) who start with the paperwork (Are you following the rules? Have you got the right Policies?), move on to implementation (What procedures do you have? Prove to me that you follow your policy), before finally landing on outcomes (How do your customers/stakeholders feel they have been treated?).
The point of this little piece is to ask you to check where on this spectrum your regulator/auditor has reached. If they are still in the ticky box phase then you need to tick the boxes, if they have progressed then you need to do something else. Personally, I am interested in outcomes and all the paperwork is incidental. however I recognise that sometimes we need to make sure the paper is there.