Especially on the a/c with the RA indications on the EADI, the brackets are only correct for 2 engines. Also, as said, with 1 engine inop, the perf limitations are such, that it's better to switch RA off, which will command a more agressive maneuvre from the other A/C. That A?C will base it's RA on your current trajectory, which is unlikely to chance on one engine.