Here's what's not allowed:
Making challenges that skip the part where the user actually achieves the achievement.
Your achievement grinder starts off with removing the leg and then skipping 3 levels. This completely invalidates the achievement about fighting with one leg and renders it meaningless.

I'm kinda inclined to remove all achievement tracking from workshop challenges, since it's so easy to exploit it. The point of achievements is to reward you for actually doing things, so removing the doing feels unfair.

Let me know if you see any other grinder levels and I'll be happy to ban them too if they offer nothing but a way to circumvent achievements. Didn't mean to target you specifically, but as a popular author yours were at the top.

How does that sound?

me: *is glad that i didn't publically allow my achivement grinder level and removed it shortly after getting the use of getting some excessively grindy achivements out of the way and not cheating any of the important ones because the only ones i can't really get are the co op ones because i constantly get frozen in place to the point where the AFK teleport doesn't work OK this is getting too long now*

Eh fair enough. The easier way would be to just disable workshop challenges counting towards the achievements. [Edit: Noticed that in the update blog after posting this]

Yep, I just removed Achievement tracking for all workshop levels. I think it's clearer that way.
No need to get into the weeds of what exactly is allowed and what isn't.

Just curious though, would achievement guides be allowed or not? [I'm have no interest in making one, but if someone else was going to make a guide on it, let's say it tells how to get all achievements including secret achievements, would that be OK or not?].

Sure, that's ok. Still leaves the achieving to the player.