BOAC, the technical aspects for the compass are as #45; however the ILS aspects might not be as clear depending on ILS course selection and EFIS display switching.
The problem of ‘inability’ revolves around the crew’s apparent failure to recall this technical detail; I surmise that this could have been due to mental workload, memory degradation with time, or that the aspect had not been taught.
mini-jumbo, re flap trim compensation, RJ vs 146.
IIRC this not quite as simple as you state. A FTC failure in the RJ reverts to the basic airframe aerodynamics; in normal manual flight 146 has a mechanical FTC system.
You may have implied this, but if not, then your description of the need to anticipate 146 trim use could be significantly greater with FTC failure.