Certificate of Eligibility – without japanese translation

Is it fine to have no japanese translation when passing documents? Because I thought my sacho in my company would help me/provide it. When I was checking the papers while in immigration, it doesn’t have. But the immigration officer check it one by one and there’s nothing wrong or looking for it. My friend told me that it is fine as long as the foreign documents is readable (Im not sure about this though). Should I make a translation since I still have a copy of my documents? Because they might ask additional requirements regarding for that? Any help will do. Thank you so much. By the way I’m submitting COE for my wife and my visa is child of japanese.