All right, this is something I've been meaning to bring up for a while, but never got to. The Emperor isn't actually named Makoto - instead, it came from Honest's phrase in chapter 4 where he says "Truly, you are the wisest of rulers" with makoto being Japanese for "truly". The manga translators misinterpreted it as "Makoto, you are the wisest of rulers".
In the anime credits and on his character sheet, he is referred to as 皇帝, "Koutei", simply meaning "Emperor". So yeah. It should be changed.