Let be realistic, if you get to choose with which people you want to play you will most certain pick the people that speak the same language, the same apply to them. The not trusting of people that have speak jp to them but the client is set to english is because when they ask for "jp only" the english people responded in jp using a translator, and face it the traslator is good but sometime the meaning of what you want to say is lost, so they decide to not trust a jp response and just check the client to see if you are trully undestanding in jp.