It's my understanding that this particular funicular system uses eight shoe brakes, where rubber pads basically clamp a metal track (from above and below) causing friction.

Hearing some local experts, they often mention that this is physically not enough to stop a 14 ton vehicle (plus passengers) going downhill when the slope is as high as 18%. So basically even if in perfectly working condition, the bake pads or wheels would just slide down the tracks as there's not enough friction for the resulting force.

Maybe something like a rack and pinion railway or some other kind of drastic metal locking mechanism are the only realistic way to prevent catastrophic events when the cable breaks/detaches, considering the masses and slopes involved here?

rack and pinion will just strip the teeth and/or disengage.

one needs just more pad area and more clamp force