I recently vacationed in Japan, and I found that using Google Translate on the phone wasn't practical because the other person would have no clue what was going on or how they are supposed to work with the app. The language auto-detect was abysmal; half the time it thought Japanese was English. They would start responding to the translated statement before the app played the chime, and I'd have to rudely interrupt them and fumble with the app to get it to start listening again. They were never sure when it was "okay" to start talking again.

In the end I tended to communicate everything I really needed by holding up the number of things I wanted on my fingers and pointing and smiling, caveman-style. They would usually know just enough English to say, "Two? Ok." Then the price of whatever I was buying would show up on the register surrounded by mystery Japanese characters, but the numbers were Western Arabic, so that was all I needed to know.

One thing I learned is that you can get by with very little knowledge of the local language to successfully travel and eat.