in this configuration, you have two options:
1. You can wire the STALL output of the TMC262 to the TMC429 stop switch input. In case you have additional mechanical stop switches, you'd need to logically OR them to the switch signals, e.g. to both inputs in order to support both directions.
or, as you propose:
2. Determine the stall condition via the CPU, by reading out stallGuard value and detecting a certain threshold.