Depends on the definition of "thing" i guess. Airbase Leeuwarden was only a very small civilian airfield started in 1938 so in a 1936 game it shouldn't exist and doesn't exist. Nazi Germany expanded it and made it a military airfield in 1940, nobody stops you from doing the same.
It would probably be for roleplaying though, in game it's location doesn't add all that much compared to exisiting airfields in Holland IMHO.