First of all as a huge Austrian zombies fan, I'm really excited that the new map will take place in Austria apparently. Maybe I should visit Schloss Hohenwerfen before the DLC release...
However, as a native German speaker I am confused with the name of this map:
The translation of "Der Eisendrachen" to "The Iron Dragon" is not completely correct because of the grammar. "Der" indicates the singular version of a word - for example "the dragon" would be "der Drache". However, the extra "n" at the end of the main word indicates either the plural version or a different meaning of the word. Therefore "the dragons" would be "DIE ...dracheN" in German. The other (correct) translation of "Drachen" in English would be "kite" (the toy for the kids) or "hang glider" - it would be a completely different word. To sum up I would translate "Der Eisendrachen" to "The Iron Kite/Hang Glider" (please correct me if I'm wrong fellow German speakers).
The relation between the ice cave near Castle Hohenwerfen and the name of the map is not clear for me (just by looking at the name). "Eisen" is "iron" in English and has nothing to do with "Eis" which would be "ice".
I can't imagine that Treyarch's translators did a bad job, maybe there are some other clues behind the name of this map...
Edit: The "iron" part could possibly refer to the ironmill "Eisenwerk Sulzenau-Werfen" near Castle Hohenwerfen which has been existing since 1770. In addition to this there is a strange factory/industrial scaffold on the right side of the picture of "Der Eisendrachen" in the background.