Unofficial, but the title roughly translate to: The Diary Of A Sage Around 40 Living In Another World.
Trivia: "Kenja" can also mean sorcerer, or Japanese slang for a virgin (specifically, virgin men over 30).
As for the translation itself, it looks ok at a glance, with a few typos. I recommend the free plugin Grammarly, which checks for grammar and spelling in a browser.