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.
Adaptation Displacement: Western fans know of the series mostly from the Akira Ishidanote Not the voice actor, mind you. manga version (the one running in Comp Ace). When the character designs for the anime adaptation where revealed, some complained that they didn't look like the "originals" at all, when actually they are pretty faithful to the Light Novel version.
Ensemble Darkhorse: Hey, remember that giant-breasted cowgirl that only appeared in a brief flashback image in episode ? Yeah, she's slowly becoming this on Pixiv.
Fixer Sue: Given the premise (in a nuthsell: fix the world) Demon Queen is bound to called this by one person or another. Given how many people she wins over, the problems she fixes with inventions we don't see her develop, and how her plans work with little difficulty, there is basis for this. However, the other heroic characters are not helpless without her.
Fridge Logic: People's titles must change with time. Head Maid must at one point have been New Maid (or something similar), and Female Knight must at one point have been Female Cadet. On that note, how would you differentiate any number of people with similar roles? Do you append numbers or adjectives to the given people?
In the LN, people with similar roles are not even given numbers. Characters do have names, but the author said the readers are not allowed to know them or supposed to be interested of names.
God-Mode Sue: In a straight-forward fighting anime Hero would be this; he can crush entire armies without suffering a single scratch, and the strongest demon warriors can't make him get serious. However, in this series he's a deconstruction. He can do all the fighting he wants but the war will continue; there will always be another Demon King to slay and the political/social/economic factors underpinning the war will keep the fighting going. Instead of fighting this show is an analysis of what overwhelmingly powerful fantasy heroes could accomplish if they focused their efforts on social reform instead of simply killing the Evil Overlord. Even here, the story points out that he has a very limited skill set, and can't even retire to teach the next generation since his natural talent ensures that he has no idea how to impart his knowledge in a way anyone else can learn. Even when he saves Demon Queen from the ancient overlords with no obvious effort on his part there are consequences to this action.
Hollywood Pudgy: The Demon Queen. It's worth noting that she's the only person who thinks she's pudgy, so this is more likely an aversion.
Certainly a Double Subverted by Head Maid, who consistently calls Demon Queen's breasts "useless meat." She laments that Demon Queen has a sexy body but a poor mindset to go with it, and eventually flat out states that Demon Queen's "useless meat" will only stop being useless when she acknowledges her worth and puts it to work (ostensibly to seduce Hero).
Magnificent Bastard: Young Merchant cooks up a plot to trick Central into selling all of its wheat to Union, which he then plans to hand over to the Southern Nations as an investment in their rapidly expanding economy. This also has the side effect of destabilizing Central, since a combination of wheat shortages and inflation means sky high prices for food. He also plans to destroy financial trust in the Central nobility when they inevitably fail to pay their handover bonds, demolishing any attempts at Central to start up a new currency system to counter the inflation. The only people outside of Union that catch on to this are Hero and Merchant Youngster.