In Dictionary > Preferences there are 65 Dictionaries listed including those listed under Other Languages even before the Shift+Click trick but no matter which were checked none appeared in the list of selected Dictionaries in the Dictionary window.

The list I gave became active when I opened Dictionary with a Shift+Click. The dictionaries in that list and the order of their appearance can be changed in Dictionaries > Preferences. I have no idea how Thai, Russian, or Polish ever got added to my dictionary list but they are no longer there. The Dictionaries themselves are downloaded from the internet when they are selected in Dictionary > Preferences so the time I spent looking for them previously was wasted. 🤷‍♂️

As to the dictionary licensing:
Originally Posted By: Apple Dictionary
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If we knew what it was we were doing, it wouldn't be called research, would it?

— Albert Einstein