It took some days - well weeks exactly - to make this work. And today I sometimes wonder, what happened…
Bottom line is, that the country/region/city feature includes a substancial number of template- and sub-template files. And even more of the same in order to translate special scandinavian letters from urls. This forum is not the right place for al this stuff.
But the main idea is straight forward. You need separate taxonomy/tempates for each route/level - ex.:
- https://udvandrerne.dk/lande/frankrig/
- https://udvandrerne.dk/regioner/frankrig/aquitaine/
- https://udvandrerne.dk/byer/frankrig/aquitaine/landiras/
The routes being lande (countries), regioner (regions) and byer (cities).
Next step is to make all links refer to not the present level/route - but the next level/route.
Then it should work.