One thing to consider is that while you may point out something worth changing, it may not actually lead to a change. I had once identified an issue on a test which contradicted the firm's diversity claims. I was assured that the issue would be taken up but nothing happened nor was I kept up to date. I also lost interest so didn't ask for an update. This year, when I took the test (and progressed to the next stage) I noticed that the issue still hadn't been resolved. My assumption is that either the issue was forgotten about or it was too expensive to correct or an alternative solution is still being researched. Despite the claims, most City law firms tend to be very hierarchical in my experience, and suggestions/requests of change/funding from the Business Services side of the firm (or "non-lawyers" as they're commonly referred to) are not necessarily prioritised. So even if the GR team would want to change, the issue might not be under their control.
If you feel strongly about the issue and have the time then I don't see the harm in sending off an email but if you're short on time and don't necessarily want to engage in chasing for replies etc then I would just focus on other things that might be more useful.