Complicated! Let me try to explain my thoughts with my limited English ...

IMHO the passage you emphasized is there to allow the different realizations of "legal persons" in different countries. E.g. in Germany the author can only(!) be a natural person and not just a legal person (in contrast to the US)

Anyway as I suspected the biggest differences are likely to be between continental Europe and the British Islands (including Ireland). The continent consists of so called "Droit d'auteur" states, where you can't transfer the right to be the author, you can only sell the right to use and sell the product.

From a historical point of view, the legal system of continental Europe stems on the French Code Civil which was imposed where Napoleon's troups came along (like driving on the right side ;-). So if one find the same legal structures and traditions in France and Germany, it's VERY likely they are alike in all Central and Western European countries, with the big exception of Britain.

I'm no lawyer, but knowing European history with all cross-influences I heavily doubt that the described New Yorker legislation can be found in continental Europe, because it would be in conflict with older legal traditions, which always emphasized the unsellable rights of the natural person who authored a creation! (UPDATE: While the mercantile anglosaxon tradition leaves more room for interpretation)

OK, so the crucial question for the EU is "How is it handled in the UK and Ireland nowadays?" Does the employer have rights on the product an employee created after work?

Most sources I read where in German, but the FSF has a special agreement called FLA which was adopted for European needs. You may want to google for the commentaries on the jurisdictional background.