Well, I think that leads to the issue. Up til the middle of High School, history books invariably ended up in "The American Century" and quickly talked about how American saved the world in WW2 and cold war, plus the follow up of that Vietnam War makes people easily draw the conclusion that WW2 was the only "just" war.
You have to realize we're talking about children who haven't really developed the nuance of grey yet, and it's too easy to think of good guy vs bad guy (Germans and Japanese). Stuff like Japanese internment was there, but was so glossed over (in a situation where it's rushed to begin with) and it took a long while to sink in what a bad thing that was and to draw the connection between that and concentration camps took a while since only evil Nazis did that.Sure, we would have gathered the US had racist policies but then putting them all together, is quite dang.
And the stuff with Churchill being a dick, well, we just don't really get any details about him beyond the Battle of Britain.
But then again, these things are often not realized by adults either, hence the "If it wasn't for us, you'd still be speaking German" nonsense that gets uttered is definitely an effect of the educational system. Well, maybe they'd be speaking Russian though....
I'm sorry, this is a long way away from "Romanticism taught in school".
Being taught that the war happened, and being instructed in several things that happened during the war, and covering specific instances of things that happened during the war to nuance one's view of the combatants, is really not the same thing as getting an unvarnished rah-rah patriotism story.
I mean, here's an anecdote that may or may not be useful to you.
Lord of the Flies, by William Golding, is a book that is taught in many American high schools in English classes. I didn't read it in school, but I taught it last year. Many of the materials that teachers provide for other teachers to teach LotF have to do with one of the central themes of the book, which is that there is evil inside every person, and that when the bonds of society break down, that evil comes out. Golding specifically got that idea in his head from serving in the Royal Navy during the war. The theme drips from practically every page of the book. When my classes read the story, we repeated it like a mantra. And to introduce that theme for the kids, I gave a quick presentation on the reasons Golding would have thought that was the case, based on the Second World War, covering the same things mentioned before: the Holocaust and the "Three Alls", sure, but also strategic bombing, nuclear weapons, internment, and so on. Students
who were paying attention thus got "the Second World War was not great for anybody" from not just history class, but English as well. And, to reiterate, this isn't just a Dachs thing, this is a thing that is extremely common for teachers to cover when they teach the topic.
Again, I'm aware that my educational history, and my work in education, may not necessarily be the most typical one, but I feel pretty confident in saying that most American history teachers do not teach a "romantic" view of the Second World War. And I feel absolutely certain that most people in America who do have a "romantic" view of the war don't get it from their high-school history teachers.
History teaching (and teaching in general) has certainly improved since I was at school. In the school I work at for example the year 4s (so 8 year olds) look at Drake from various sources and have to say, giving reasons, if they consider him a hero or villain, or somewhere in between and justify why. The biggest problem is time, too many subjects, too many priorities (haven't governments realised yet that if you make 3 or 4 subjects priorities none of them end up being the priority?).
It all depends on what the government thinks is a necessary baseline history education for a functioning adult in society.