I'm still thinking it's Bluetooth. from the manual:
You can also use the Lionel Universal Remote 6-83071 with the 6-30218 Bluetooth set.Operation will be the same as with your Bluetooth set remote
The Universal Remote will communicate exclusively to the Bluetooth PE set which means the Universal Remote will need to also Exclusively use the same Bluetooth signal to communicate to the announcement car.
You can't plaster Bluetooth logos on devices that do not use Bluetooth. There are legal reasons behind that.
What's the part number of the command version Lionel offers now? I've only been able to locate the one that has conventional operation only via the bell button.