I'm pretty sure that most (if not all) of the words are nonsense words that are just hard for people to say.
You are right, Jonathan. I asked for help to some friends that know japasene (so them told me!) and I have reworked the orders to obtain more complicated words. In example, "dark green" or "light green", I dont remember. But this only for the first set of the four. The others three are composed by simply nonsense words that "sounds" japanese for us. Some of them starting with some letters, so is more difficult the speak correctly and players have to speak entirely (even simple games require some tricks) I dont remember if them are used on the original Cocktail version. Here you can find the first demo of the game, some years ago: