For AC signals, like speaker crossover networks, always use non-polarized because AC is continuously reversing polarity.
If you use a polarized electrolytic in a crossover network you probably won’t be able to hear the difference, however measurements will show the difference (human hearing is a terrible measuring instrument).
After an uncertain amount of time (the manufacturers don’t test this since it’s not an approved use for their product) the values will start drifting making the circuit operate even further away way from the intended operation. Again, you may or may not hear the problem but it will be measurable.
The Nichicon “Fine Gold” series capacitors are for use in the DC portions, especially power supplies, of audio equipment not in the signal chain.