These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Genius Bonus: More like historian bonus, as the more knowledge about history you have, the more events referenced in their songs you're gonna understand. This pretty much encourages the listener to do a lot of research. A sabaton, by the way, is the metal shoe in a suit of armor.
Poles Love Sabaton: Oh boy, how very much. Thanks to their 40:1, they've found their way into mainstream news and do concerts in museums. Here's the Aesop: when you're a dabbling metaller, and want to quickly and surely gain some notoriety, make a song about brave Polish people. They seem to realise this (heh eh heh heh), as they've now let out Uprising.
Also in Russia, thanks to Stalingrad, Panzerkampf and Attero Dominatus.
They gained a whole lot of popularity in Brazil due to "Smoking Snakes" recently, to the point that it's often lampshaded by Brazilians themselves that Sabaton brings up something that should be taught in classes and just isn't.
Lost in Translation: There is a distinct difference in tone between the Swedish and English versions of "Carolus Rex". The English version is a pretty positive badass-praising album in regular Sabaton-style. The Swedish version is a far more solemn affair, focusing more on the effects of the war on soldiers, civilians and countries, and doesn't shy away from depicting atrocities on either side. For comparison: The bridge from Killing Ground
English version: See the Caroleans standing tall/ All for one and one for all/ Enemies fall at their feet/ Begging for their mercy/ See the Caroleans standing tall/ Conquer lands and slaughter all/ Enemies fall at their feet/ Victory and great defeat
Direct translation of Swedish version: See the Russian surrender, beg for mercy/ The Swede violates the code of war/ Caroleans take their revenge/ Slaughter their prisoners/ See the Russian surrender, beg for mercy/ Mass murder, not heroic deed/ Caroleans take their revenge/ Honor is lost
Misaimed Fandom - there's potential for that, for obvious reasons. One of their songs is called "Wehrmacht".
Music to Invade Poland to: Sabaton get this a lot. They make bombastic power metal, their vocalist rolls his Rs in a very particular way, and most of their songs are about WW I and II, quite a few of them from the perspective of German forces. Disregard that they have several songs from the perspective of the nations fighting against Nazi Germany as well as definite anti-war anthems, and that their eight minute epic about the Nazi's rise to power is called Rise of Evil. Oh, and the band is Swedish.
All things considered "Music to Defend Poland to" would be a more apt description, considering their Polish fanbase and songs like 40:1 and Uprising.