@Cernel The amount of real estate that a name takes up on the map also matters. If the name is too long and ends up bleeding over into neighboring territories or having to be shrunk to a barely readable font size, the result ends up looking ugly.
Bohemia works as a shorthand that was in common use for Bohemia-Moravia. There’s no problem with doing that - notice we’re not obliged to refer to the UK player as “United Kingdom of Great Britain and Ireland” in all contexts.
Hesse actually looks out of place now as Germany’s western border territory - the real state of Hesse doesn’t touch Belgium or France at all. Either Rhineland or Westphalia would be more appropriate for that.