Each language in Scrutix has its own dictionary, inside the app. The words to find are common words of that language, and the filler letters are checked against its full dictionary.
Word language and app language
Word language, on the home screen and in Settings, chooses the language the hidden words come from. App language chooses the language of the buttons and menus. The two are separate: you can play with Spanish words in an English app.
The first time, both follow the language of your phone. On the home screen, changing the word language while a grid is in progress asks first: that grid is abandoned.
Common words, without accents
The words to find have 4 to 8 letters. They are common words, with no proper nouns. Accents are left out, as on most printed word searches: É is written E, Ü is written U.