Test for the best is already in use on the Mario Party 8 page itself
i respect that but if you look at from certain peoples perspectives it shows that they are #1 for a specific category this way but filter its a completely different way due to "hidden times" take me for example it shows im #4 overall but #1 for normal this way until i filter it, when i filter it shows my as #3 due to Simon and Echo having better times in Easy rather than normal. As for your statement Other Mario Party games could actually do this very same thing for the same similar reasons i checked every MP that has all boards listed has them separated by difficulty. MP6 is the only one that does this.
ideally for the minigame portions play Party Mode with save after every turn to unlock everything EXCEPT for Stage Fright (1vs3) Burnstile (2vs2) Wrassling Rapids (Battle) Freeze Frame (4player) if one of these comes up just restart console until they dont come up. wheel will always pick unclaimed minigames just make sure you lose them as its faster and you get less coins.
i know for a fact 7 has single board record on the site.
source: https://www.speedrun.com/marioparty7/individual_levels
knowing how much i hate myself ill probably end up running the Quadfecta