If that is the official address, it should be on the map, so you should have to investigate exactly one cottage. It's not like street numbers are always simple

If that is the official address, it should be on the map, so you should have to investigate exactly one cottage. It's not like street numbers are always simple and sequential either. I have streets that become other streets in the middle. I have streets that end in a T-intersection, then continue from another T-intersection half a km away. Addressing globally has never been anything close to e.g. Manhattan's grid system. As long as that town's official addressing system works the way the locals say it does, deliveries should arrive as normal with no hassle. And that town isn't even unique within the EU, there are plenty of towns on my side of the continent that just number their buildings and don't assign them street addresses.