But did either Western or Eastern Germany have such huge battleships in the post-war era?
no, the largest units in both postwar navies were destroyers and frigates.
But this applies to most navies. If I remember correctly only Great Britain, France, USA, UdSSR, Turkey and two or three south american navies have used Battleships/Battlecruisers after WWII.
In the alternative history of Civ it is possible to meet a battleship under command of the Maya or Mongols.
Or would you like to limit the use of capital ships to those navies, who used them in real history? That would put most civilisations in disadvantage.
Currently I am using besides generic some country specific capital ships.
For example on the "german" shipbranch (used by Germany, Ottoman Empire and Byzantium - because of SMS Goeben, later Yavuz) are available
- German Dreadnought (Bayern Class)
- German Battlecruiser (Mackensen Class)
- (generic) Battleship (South Dakota Class)
On the other side the "french" ship branch (used by Celtic Nation and France) included
- (generic) Dreadnought (Nagato Class)
- no Battlecruiser
- French Battleship (Richelieu Class)
There is also a "british", "japanese" and a "US" Ship branch, while at least half of the civilisations are limited to the generic dreadnoughts and battleships only.
Beside that I feel very uncomfortable with NS symbols on units in a computer game.