u/Nokayo

I'm mostly interested in the former but you can also suggest some that has only one (obviously I mean artists with many albums here).

For me these two:

Empyrium - I'm a big fan of neofolk and some of their records (actually three of them - A Winter Sunset..., Weiland, Where at Night the Wood Grouse Plays) always seemed to be for me like real stand-outs in the genre ... yet not a single one of Empyrium is bolded. My favourite album is Where at Night the Wood Grouse Plays from 1999, a very touching one and it's pure neofolk/dark folk - not doom metal mixed with neofolk like some other ones. Songs of Moors and Misty Fields is their highest ranked one #177 for 1997.

Russian Circles - post-rock/post-metal band

Highest ranked album is Station from 2008 #253

One would be the rules for quidditch, I've thought it was dumb already as a kid for the match to be finished by the seeker catching the golden snitch and earning 150 points which is 15 times as much as a goal is worth of. I'd make the official rules of quidditch to be more relaxed and for players individual contribution matter more as rarely matches ended up as losses or draws with a losing team being the one with a snitch. Let's make it 50 points or get some time limit on catching it, the ordinary clocks would be too muggle-like to mark it but one could find some good solution. Just make it more like the quidditch played in the Wesleys' family backyard.

Another would be making teleportation more difficult/risky or nix it entirely. I know it was risky, many wizards were not capable of it and it was mentioned a couple of times in the book and had factored in the events of the final book but still ... I remember thinking it was silly that a lot of wizards would travel by Knight Bus or with brooms/magical cars/carpets etc. when they could catch a Portkey or use help of a wizard that had the teleporting skill. And I also remember thinking that it would be senseless for wizard children from Hogsmeade and that area of Britain to travel all the way to London to take a ride back to Hogwarts (but I know it served socialising purposes too and helped to ascertain that they'd arrive roughly at the same time). And a lot of such lore plotholes can be simply ascribed to Rowling not caring much about their possible presence, especially as the first few novels were more clearly children's literature

And I'd make a Crookshanks a family cat of Potters family cannon (it's a fan theory that does add up and which I find very cool).

The messy, illogical wizarding currency ... I was never bothered by it but it indeed makes little sense just like some wizards being seemingly poor.