I would recommend on using a local word list. I created a prototype word game some years back with ~172k English words in a simple .txt file. From what I remember, there was no noticeable delay or lag of any kind when going through the dictionary.
Also, as you already pointed out, figuring out foreign languages can be a real hassle. Finding dictionaries is easy enough, removing profanity as well, but then you’d have to actually understand the typical word structure in each language in order to know what alphabets to provide the player with and in what quantities, how to give points for different languages, setup score requirements, etc. It just gets very difficult without a proficient speaker as a part of the development team and you’d require extensive testing.
I’d recommend just focusing on developing a word game in your own language at first. If the game finds traction, then look into translations.