So apparently this is a feature, not a bug. Just changed my computer language to Dutch, and then the first time I used spotlight this appeared:
It states that local searches are done and that certain information is sent to Apple "to make the results more relevant". You can switch this off, but that is apparently all you can change. This explains why this was not seen by beta-testers: undoubtedly it was, but since Apple is proud of this feature, they just ignored it. Although they could at least haven given first users a warning: set your language to the local one or web searches will not work.
But I do not want this at all. I want my regional preferences (formats of currency, dates and times) to be Dutch and my computer language English.
Just a few tests of the Dutch spotlight settings gave some really silly results. "Krokodil" turned out to be a drug, not the animal with the same name, "Macintosh" did not produce a computer or even an apple (the fruit), but the "Macintosh retail group", with a Dutch website, and the English word "Elephant", which gave "Energy saver" before now lead to "Energiestand" in the Dutch system preferences. Yes, I can see that a few characters are the same, but how bad a typist do you have to be to get it that wrong. There is nothing sillier than computers trying to be smart.
I hope this will be fixed, but I doubt it.