The procedures do appear to be poor.
Quite why hot wheel detectors are found "unreliable" is difficult to understand, beyond maybe the cheapest such equipment has been purchased. In the USA they have long been deployed for multiple functions ("Defect Detectors"), and are felt reliable. Furthermore the way of transmitting any failure, as both the RAIB report and the comments above indicate, is ludicrous (passing defects recorded locally, but someone has to go out to site periodically to download them ... I mean, come on). The USA ones for a long time now have been "talking detectors", which among other things make pre-set announcements over the train radio system of any fault, so it comes to everyone's attention instantly and even before the end of the train has passed the loco driver and the dispatcher has heard exactly what the problem is, on which wheel. It's not rocket science, and the RAIB really should have pointed out that such thoroughly reliable equipment is available off the shelf.
Defect detectors | Trains Magazine
I once again had hoped that, with all the different organisations subcontracting to one another, the RAIB would look at the commercial side of how the various organisations get selected and paid, because I suspect the "bottom bidder" approach to selecting the variouis companies. Certainly for an independent company to be required to validate those doing the work, and then doing blow all to actually check this, should have been pointed out even more forcefully. Then there was the interim report on poor maintenance arrangements, which RAIB went back to check later and found that nothing beyond the bare minimum of what they had pointed out had been done.
I wonder that the wagon owner was allowed back on the national network after all this.