Haha, I hadn't got as far as Hiei coming out with the wrong name, but I had noticed the names for the Kongos under the BCs instead of the BBs (and popped a thread up about it, although I hadn't got around to testing it in-game, wanted to post before I forgot). I agree that if Hiei is a BB, then then the four Kongo names should be in the BB slot - but I also think if Hood is a BC, then the four Kongos should be BCs as well (and they'll be that way in the basic mod I'm putting together - I couldn't live with m'self putting in a naval mod and calling them BCs).
If it helps, I used the Kii class (planned but scuppered because of the Washington Treaty) for my 1936 BBs, with the description
"The Kii class were to be Japan's first true fast battleships. More heavily armoured than contemporary battlecruisers, but similarly as fast. They weren't built due to the Washington Naval Treaty of 1922, and when Japan did recommence battleship construction, they opted for the super-heavy Yamato class."
Kongo became my BC, with the description:
"The Kongo class were built for the IJN just before World War I as battlecruisers, and were heavily modernized in the late 1930s. While they were reclassified as first rate fast battleships, their capabilities were still those of a heavily armoured battlecruiser, rather than a modern battlehip."
It is an ongoing point of debate, but I'm going with functional definitions of ships, rather than what particular navies called ships at the time.