Tukukkk

Why is the American magical government called

American Ministry of Magic

in the second movie? To me if anything it should be MACUSA or maybe the American Department of Magic like the real world example Department of Defense, etc. Maybe Rowling doesn't know how our government works or she did not research like usual.

The subtitle is merely for the audience's benefit and convenience. The official title of the body is "The Magical Congress of the United States of America (MACUSA)" however the majority of viewers wouldn't necessarily know what the acronym means. Note that the screenplay gives its full title

SCENE 1

EXT. NEW YORK, AMERICAN MINISTRY OF MAGIC—1927—NIGHT

AERIAL SHOT of New York and MACUSA building.

By the same token, the subtitle later in the film reads

French Ministry of Magic

Whereas we know from various factbooks that the official title of the body is "(le) Ministère des Affaires Magiques de la France". Again, the majority of viewers don't speak French so it's convenient to have the film explain where the characters are in a way that audiences (young and old) can easily comprehend.

If the MACUSA was founded in 1693 if I remember right, probably using a different name since there wasn't any USA yet, it would have been when the British colonies in North America were colonies of the English government, and the Kingdom of England in 1693 had ministries instead of departments.

So the magical government that later used the name MACUSA could have created a ministry to interact with the famous governments of the English colonies when necessary. And if thy did so before the American Revolution in 1775-1783 they would have called it a ministry. And maybe they didn't change the name of the ministry to department after the federal government of the USA was established in 1789.

Perhaps they wanted to avoid following the latest trends in muggle government and remain detached from muggle practices.