I very much question your premise that it is "so overlooked in academic European history". You will not find any academic work of history on the period where it is not covered.

Having studied early modern history, I am well aware of that Sweden was a major power, so I don't really see where you are coming from.

Do english speaking people really call him Charles in english? Since there are people in english speaking countries called Carl, it can't be so hard to call him Karl the 12th (which was his name), I imagine.

So its becoming obvious to me that this is less a national problem and more a problem localized to Maryland private schools. Thanks for clearing this up for me!