When I asked Carta Mundi Belgium about this, they said that the US print runs of European languages, were because WotC wanted to release the sets quickly, and couldn’t wait for Belgium to print them.
This seems to indicate that the US print runs were first.
The new info about the UV Color facility, helps to explain why Belgium would have been slow to print them.
Apparently Belgium needed some time to get a UV Press, so that they would be able to make holo cards.
The different Portuguese print runs, could also be due to having different sales regions.
Perhaps the US Portuguese run went to Brazil, and the Belgium Portuguese run went to Portugal?
I’ve seen WotC take shortcuts like that on several Magic sets.
Sometimes if they were rereleasing a product with only a small change, they wouldn’t update the copyright date.
Take the copyright dates with a grain of salt. They’re not necessarily the year a product was released.
The UK Base Set with 2000 copyright, was printed in November 1999.
Magic has some 1994 copyright sets, which weren’t released until March 1995, due to production delays.
A rereleased product, might have the same copyright as the original release, which can save time for WotC.