Well, the documentation is wrong. These layers obviously have tooltips, but they are not using the service `identify`I mentionned, because they are GeoJSON layers. The error message from the service ("No GeoTable was found for ch.bakom.mobil-antennenstandorte-gsm") is correct, but misleading in the context.
Regarding your problem, as you cannot use the service, you'll have to do it yourself. If you need it, I may provide you a simple example on how to do it. Do you work in the browser or backend?
I will correct the documentation.