That sounds very annoying the cats spraying just there! I’m sorry I don’t know about cat urine neutralising spray. It might depend what’s in it. I have read that half water half white vinegar can neutralise cat urine, but then that smells too, in a different way (maybe not quite so bad?) – but you could put that into a spray bottle. Does rain make any difference to the smell? We’ve had quite a bit here recently.
Sorry not to be more help!