I agree
@SparkyChick assuming it really is routed with the live conductors all the way but, it's one of those things where everyone knows it's weird like over sleeving green and yellow cores of a flex with brown, and you wouldn't want to have to justify it in court (hence the good luck) but the regs seem to allow it but not totally explicitly.
The definition of wiring system...
Wiring system. An assembly made up of cable or busbars and parts which secure and, if necessary, enclose the cable or busbars.
Given it's a domestic situation and is likely to be wired in twin and earth (the wiring system), the CPC for the circuit will be routed with the live conductors (or in close proximity - in back boxes) along it's entire length.
All that's different in this case is the CPC is sourced at two points. One at the origin of the circuit and then another at the end to provide a better connection to the earthing system. The CPC for the circuit (bearing in mind the circuit ends where the live conductors terminate) is contained in the same wiring system (the cable) along it's entire length (valid assumption).
There's nothing weird about that, the ideal solution is to find the bad connection and fix it but sometimes ripping a customers house apart is not an option so you have to go for a less than ideal solution.
The only real point of concern is the current carrying capacity of the CPC used as the source of earth. Total CSA in a typical ring final is 3 sq. mm, so unless the cooker circuit is 10mm, this is more than ample to handle fault currents.
I don't think good luck is required, the OP made an educated decision and has improved the safety of the installation. I struggle to see how such a move could come back and bite him in the bum later.
As for sleeving yellow/green with brown in a flex... that's not weird, it's plain wrong. If you need three live cores you should be using an appropriate 4 core flex.
I'm also curious about which part
@buzzlightyear disagrees with in my post