Hello butitsmyname,
I can confirm the issue with the Merriam-Webster Spanish translation dictionary.
It was the same for me, after the upgrade (to the PaperWhite in my case) the Merriam-Webster stopped working. Its language code IS English, for sure.
However, since the upgrade, they included the diccionario de la real academia espaņola into the default list of available dictionaries. So personally, I don't need it any longer. It actually comes in quite handy to have a Spanish dictionary with EN language code for some authors (like Steinbeck for instance ....).
What you could try is using Java Mobi Metadata Editor (
https://www.mobileread.com/forums/sho...d.php?t=165729) and change the language code yourself. Prerequisite for that, of course, is applying the magic of Alf beforehand.