Put them directly adjacent to it if you want, or on it. Frankly labels would improve the appearance of those!
Beauty is in the eye of the beholder.
Whilst you often give sensible and wisely advice, I think your just digging a hole for yourself here. In a domestic installation (not sure if is the case with this thread), covering the lid with warning labels, in most circumstances will look unsightly and unnecessary.
Reg 514.9 Diagrams & Documentations; for all the 'labels', the most the that is said 'fixed in a prominent position at or near the original of the installation', 'easily legible', 'indelible characters', 'not smaller than illustrated', 'affixed at'. Reg 514.9.1, says 'a durable copy of the schedule...........shall be provided
within or adjacent.....'.
The reg doesn't say, these labels most not be mounted on the inside of the lid of a CU. Most manufacturers label mounting instructions, demonstrate them being mounted on the inside of the lid of A3 CU's.
So unless BS7671 decides that this is a 'disastrous loophole', and manufacturers are riding rough shod over the Regs, and this situation needs rectifying in the 18th Edition, there is no reason why these labels cannot be mounted on the inside of a lid of a CU.