You make some good points. As the article said,
There are some questions on the test that are a bit dated and may justifiably stump many. Questions like the 3 largest states would have a different answer today than then. A question like the number of presidents who died in office is different today than then. Also the names of some countries is different today than then. Most of the questions however apply today as it did then so there should be no excuse that if students could successfully do the test then they should now.
Even given that, your statement that US history has largely always been propaganda is quite true, and the truth can be seen in the vigor with which the forces of reaction attack and dismantle history curricula where they hold sway. Apparently now even AP US history.
I only took part of the test. The straightforward arithmetic is easy enough, and seems to test really whether you know how to think about the problem or not. Which is pretty basic. Although given changes in the teaching of math, I wonder if a new generation could do the computation part, which is the easiest part of the problem.
For my money, the part about civil government is most telling. Few adults today and probably fewer young people could answer more than three out of ten correctly.
Agreed.

Général Toussaint Louverture
The contribution that a certain (former African slave) military General from Haiti made in convincing the conniving English that the time was right for them to try to give the American upstarts "what fer" is absent form American History books, even in Academic circles. They just don't want to go there. Had that General not defeated the cream of Napoleon's armies sent to crush the Haitian revolution, England would not have dared attack the USA due to the alliance between France and the USA. There are a lot of details in that story. White Europeans close ranks when the Africans get "uppity", so to speak

.
Thomas Jefferson violated he U.S. Constitution by authorizing money for the bastard white French Plantation slave owners that fled to New York so they could buy weapons to fight the slaves. Instead of cheering the FACT that Haiti was doing to France EXACTLY what the USA had done to England, the racist Jefferson got his drawers in a bunch worrying that the slave profit gravy train in the USA might get compromised. So he promptly discarded all his high flying constitutional rhetoric for the holy purpose of white supremacy.
Even the British, who HATED the French, sent some troops to Haiti to "help" the French crush the Revolution. The British tried to use "diplomacy" (money, intrigue and treachery to fool the "monkeys") more than open warfare, however.
The bottom line is, NO Revolution in Haiti would have meant NO War of 1812.
Haiti later gave Simon Bolivar the inspiration, sanctuary, and help to organize South America in order to kick the Spanish out.

The empathy based portion of the world owes a LOT to Haiti. But good luck trying to convince 90% of Americans of that.