Day after day, worn out by communicating with foreign employees...
Communication barriers with foreign employees are problems that arise not from differences in language ability but from each side being unable to see the other's "obvious" assumptions about reporting, confirmation and quality standards.
No matter how many times you explain, the same questions come back. They said "I understand," yet the finished work is completely different. No report comes, so you go and check yourself, only to be told "there are no problems," and later a major problem comes to light.
Even with employees who speak Japanese reasonably well, subtle nuances don't get across. You said "it's urgent," yet nothing has moved by the following week. You said "do it carefully," and now they spend far too much time on it.
Communicating in English is not the answer either. English is not their native language either. When both sides speak a second language, it looks as if you understand each other, but in fact there are subtle gaps. And you can't notice those gaps.
"Can't this go a little more smoothly?" You are probably not the only one thinking that.