I have no idea what the "universal 20" is supposed to be, nor do I see why this pattern would be the only one.
cf.
de små fyra
they.PRON small.AD four.CARD
the four small ones
de fyra små
they.PRON four.CARD small.AD
the four small ones
de små fyra husen
they.PRON small.AD four.CARD houses.SB
the four small houses
de fyra husen små
they.PRON four.CARD houses.SB small.AD
the four small houses
fyra husen de små
four.CARD houses.SB they.PRON small.AD
the four small houses
I don't know what a Swedish (as in from Sweden) linguist would say, but I don't see this word order as strange at all. Word order can be quite flexible, even without the full-fledge inflectional system of Old Norse or Proto-Germanic.
The same probably works in all Norse languages, and likely in German and related languages. I'm a little unsure about English. And when you get to languages like Latin you can throw it right out the window, with the incredibly flexible word order.