An interesting discussion. I am not familiar with the particular equipment, but would it be correct to assume that there is both an ALT SEL readout on the FCU near the selector, and a readout on the PFD ?
If so, this follows general design principles (SAE S7 recommendations circa 80/90s), where annunciations should be provided both at the point of selection (next to the knob) and at ‘the point of operation’ (PFD for inst flying / monitoring).
The current use of these systems appears to contradict the design assumptions; apparently due to the risk of mis selection. Thus if true, procedures have been introduced to overcome a design weakness, yet we have to and can accommodate many weaknesses because no system is perfect, but this should not be at the expense of introducing another error: – reaching for the selector knob without looking and choosing an incorrect control; or looking at the selector then back to the PFD with associated increased workload.
There may be no answer to such dilemmas, but it would be interesting to understand some of the rationale and balancing safety cases.