On top of all this, I know that some European countries used black instead of green as the designated color for Starboard buoys. IIRC correct colors in the British Isles for many years was red for port, black for starboard, and yellow for wreck buoys.
After WWII green for starboard became standard worldwide (I think!)

Before WWII ended buoy systems were, in fact, very confusing due to lack of consistency worldwide....