Unfortunately I don´t own Bismarck or Tirpitz. I have Missouri and New Jersey and those kits are exact copies of the 1/350 Tamiya kits, just in a smaller scale. No soft or missing detail, no shortcuts, good fit. Easily among the best Battleship kits in 1/400, on par with Heller´s Richelieu, Jean Bart, Strasbourg and Dunkerque.
In Japan these kits are marketed by ARII, so I assume that they are NOT illegal copies of any sort. Now my guess would be that Tirpitz and Bismarck are downscaled Tamiyas as well, but some people have complained about a poor fit and not-so-great detail, especially on the boats.
The HLJ website has small images of the ARII versions and from what I can see Bismarck and Tirpitz have the same level of detail as the Tamiya kits, e.g. the vents on the front turrets are all there, so they are surely not identical to the Heller kits. From what I see I´d say give them a try. I am tempted to buy them, too, but the Heller Bismarck and Tirpitz already in the basement, I just have no idea what to do with more than two of the class...