That is a very old product. Aristocraft came out with the Crest Train Engineer Revolution to replace it. After Aristocraft went belly up, some people tried to continue on with the Crest product. They did for awhile. They couldn't manage to do it. The people who built the Train Engineer for them took it over. They have had it for quite awhile. I think it is a very good product. I use it. Here is a link to their web site:
They also have a new product for DCC. The Train Engineer has sound built in. The sound is not fancy, but it has basics like bell and a whistle or horn. It also has outputs to control other things like smoke.
The Revolution product has 5 amp and 15 amp receivers. They may be used onboard. The DCC product has 5 amp receiver/booster. There is a 15 amp receiver/booster in the works.
I don't know if anyone could tell you for sure if it would work under your circumstance. Outdoor range is up to 400 or 500 feet. It operates on 2.4 GHZ.
The web site has a lot of information such as manuals and wiring diagrams.
I never saw where you said what the interior walls of your house were made of. You could try emailing the Tain Engineer people and see what they say. Sometimes emails just go by the wayside. It would probably be an expensive phone call.
Now that you have a name of a product, maybe you could ask around in Switzerland and see if anyone has used it.