I don't know what the reference to the DE version means. But I can say that it works perfectly in Switzerland. I recently bought it and put it into operation at a customer's house.
Plugs are 2-pole, so they fit in Switzerland as well as in the EU.

That means it comes with a German plug!

it all worked in Switzerland

Don't get confused. It definitely works in Germany, France and Italy without an adapter.
Power (230VAC/50Hz) = EURO (2-pole).
PhoneLine(analogue) = Western RJ-11(6P2C), the middle two poles are occupied.

I wonder why Galaxus gives this hint, it's not even mentioned in the technical data of the manufacturer Gigaset.
Be brave!