Static magnetic field does not make any impact to our electronics ... IF ... wires do not move. So it will be good to fix all cables to model, not only because of magnets, but also because of their breaking in connectors and because active timers can "hear" how the move.
Magnets in rotor of motor, can and does induce voltage in wires, but magnetic field is enclosed inside the motor (one side of magnet is oriented to iron ring and the other to stator ), so it should not go "out". However it is not always perfectly done, so better is not to have sensitive wires close to rotating motor.
And what are sensitive wires? Most of the system is 5V digital, so it is not anything sensitive, but active timers with sensors have such parts and wires, so it is good to have sensors far from motor ... means back of battery at CG