PDC, When you test, you do so against the current regs.
You are responsible for deciding if any remedial work is required and how urgent it is. You do so by marking faults with codes 1 to 4. It's irrelevant if the installation would have passed a test to 12th edition regs.
I do test against the current regs, but the regs are not retrospective, so if something was installed to the 12th edition and has not been touched since then there is no requirement for remedial works. The fault codes you mention are NICEIC, which is not required by our system. I report on anything that I find and the engineers decide whether remedial actyion is required. The only faults that I rectify immediately are where there is a danger to life or imminent fire. Even then, I dont repair the fault, only make it safe.