That read about like I expected. Even with additional "small boys" in the mix, I'd still give the IJN the edge, those ships just wouldn't be evenly matched (just my thoughts).
Exactly. What should be noted is, that the German ships had been great in WW1 and that gave the Nazis a good start into WW2 ... but the ship designs of WW2 had been utterly obsolete. Especially because of bad strategic planning. Even when they ignored the Washington treaty, the core systems had been based on WW1 technology.
The only true innovation of the German navy in WW2 had been the submarine class XXI... it just arrived far too late.
But also: I doubt the Japanese battleships had really such a great advantage as claimed there. They look great in numbers, but it is also easily visible, that those numbers don't work together with conflicts. Especially since nobody ever witnessed the gunnery of a Yamato. The few observations are anti-aircraft gunnery and the 18" guns had been performing very poorly there in the VERY few shots fired. The theoretically possible 550m CEP of the 18" guns should have been even less in a real battle (Yes, that means that there could be two Bismarck class battleships next to each other broadside to broadside, not moving or maneuvering - and less than 5% of the projectiles of a 18" gun would hit them). The turrets only rotated at 2° per second, enough for long range engagement, but too slow for a melee - you could just switch to local control and fire at the next best target you get. The rest of the IJN fleet was also stuck in WW1 and the IJN did not really have much joy in their torpedo advantage in real battles. They simply had too few torpedoes for such kinds of engagements. Especially at the maximum range, you needed many torpedoes for even having a tiny chance of hitting a battleship.
In practical reality, I think the battle between the rather antique but solid Bismarck and the overpowered Yamato could also have gone for the German ships. The Japanese ships would have been impossible to sink with 15" projectiles, maybe. They had been able to absorb a lot of punishment before sinking in their real battles. But also, it could have been much easier possible to make a Yamato class unable to fight, which is enough. The fire control systems had been very vulnerable there, the Yamatos had been very quickly harmless moving targets against aircraft. And again, a single 18" projectile at the stern of a Bismarck class could have made it unable to maneuver and should be able to knock a turret out. But somehow, the Yamato class really rather leaves the feeling of a feigned giant - the closer you get to it, the smaller it looks. I doubt that the Yamato would have had even a small chance in a battle against an Iowa.
But again, that would be something I would really like to somehow simulate with some comparable engine....
And speaking of WW1, the Derfflinger class is also a pretty ship of that era: