Sometimes, writers really just fill every nook and cranny of their world with detail. I am genuinely so surprised that this series has so much lore to everything. But I suppose that's what carries it. The incredible internal consistency had to stem from something.
What's really smart is the fact that a ton of stuff is spontaneous, made up as they go, but Sensei hardly ever retcons, but instead just takes absolutely everything that has come up, and brings it back at some point.
Chekhov's EVERYTHING.
Like, the Many-ears aren't even in it for a long time, despite "magical tools that even people with no mana can use" being a plot point. I'm certain that she planned out their lore deeply, first considering a bunch of factors, but those factors also tell me that she didn't come up with them until pretty deep in the series.
I'd say she had reason to start that line of thought around when Kiriwo shows up? I think that's the first time we see a kiddush cup, right? (And again, I have never in my life seen a gold one. I've seen glass ones, but not many. Generally silver-plated. Thickly plated (multiple mm).
Anyway, sensei's seems to treat the series like a snowball. You can keep adding, but you can't remove.
Oh,no... Rock being a sleaze is gonna come baaaack. He tried to kiss a child while in disguise!!!
Anyway...