Actually, the kiosks will probably show pictures of the food and no words.
For example, a meal deal with a large fry and large drink, will show a large drink, large fries, sandwich and the international standard for arrows will be used navigate from page to page. The tricky part will be paying but most people can swipe their card — just flash a picture of a credit card. Cash might be trickier.
It should be fairly idiot proof.
I doubt cash will exist in 5 years, because we have the technology to replace it. People only use cash now when the they have to otherwise it is swipe a card or smart device.
They'll just keep making better idiots.