All I will say is...
a) all guard training I have ever been involved in has required spot checks to ensure candidates are familiar with their line of route from the vantage point of wherever they are onboard the train, including knowing which major structures, level crossings and station platforms they are passing.
b) the driver is so vulnerable that a second person onboard really should be able to pinpoint the location of an incident* or, for that matter, any suspected defect.
c) knowing exactly where you are, or not, is critical to resolving an incident safely, as demonstrated.
d) I don't tend to lie about train crew skills, seeing as I have seen what they can and cannot do on countless occasions on the ground, in a control room, and as a passenger.
* See here:
https://assets.publishing.service.gov.uk/media/547c8feced915d4c10000159/R082011_110407_Lavington.pdf
The Train Manager onboard the HST in question was the only person who, when required, provided a fully accurate description of the train's location - page 21.