I mean this with no disrespect - but this is potentially the worst category idea I've seen in these forums. From literally every perspective I could imagine it's the worst idea I think. Relevancy to the game, enjoyability, likelihood to be ran... This feels more like a challenge run than an actual speedrun. Low% akin, but just an objectively worse condition to be met.
The master of peppa pig memory game claps back, our battle will be legendary.
Also, if you want your original achievements for terraria back you and verify the Integrity and they will all come back in.
Resetting your achievements, you turn off Cloud Save for steam/terraria, delete achievements-steam.dat here: C:\Program Files\Steam\userdata<YourAccountID>\105600\remote, then when you reopen terraria you should have achievements reset. Your steam achievements remain though.
Journey fishing only took me like an hour, you can get a quest fish, skip to the next day, and keep cycling until you have like 1/4 of the fish in the entire treasure fish pool (There are like 60 or 80 of them total). Then hard dupe them and you have enough to just grab any fish you need from your journey menu. The worse achievement IMO was the walking one and the Slime Rain one, as you don't walk a lot once you get the star from ML and the Slime Rain is REALLY rare, it can sometimes be hours until you get one. Make sure if you get one early on you DON'T MISS IT! Besides that, some other ones that were a little annoying were pumpkin and frost moons, just because you have to go out of your way for them. The max HP and Mana Stars. The 2nd evil boss, so you need both EoW and Brain. Besides that you could easily get a faster time than what I got, I went into it with no idea what I was needing to do.