I've just completed my first patrol.
While doing so I noticed some things.
Some smaller Japanese merchant ships did not fly any flag at all. (I've made some screenshots of that but somehow they are not in my sh4 main directory.....

)
Another thing was that all Japanese aircraft were blind.
After some time I' didn't even bother to dive anymore.
The patrol was a success regardless and when I returned to my port on Cylon I found some ships that have surely been involved in the Manhattan project.
I also noticed, that the loading times of the game have drastically increased (please don't take this as a complaint, it's just something I've noticed).
Apart from that everything worked fine.
Thanks to everyone involved for making this nice mod.