I'm glad it exists, though I've never felt the need to use it.

I mentally process the slurs as dialogue: stuff our cast of edgy, poorly-socialised 13-year-olds would realistically say and think, due to being edgy, poorly-socialised 13-year-olds. It's thing. I heard much worse growing up; amongst themselves, early teens spray out "bad words" like a sodding firehose, and they don't really get that slurs are actually worse than swearwords until they're older. (Often due to the bad influence of their elders.)

But I totally get that not everyone can brush this off in the same way. It must be unpleasant to see your favourite characters tossing around bigoted insults that target you, and maybe I got off lightly - "autistic cat-girl"? Pfft. Try harder, Karkat. When I write Homestuck fic, I avoid slurs like the plague. I don't want to make anyone feel bad, even if that forces the dialogue to be out of character.

The awkwardness of some of the replacements in the mod isn't 100% a bad thing: it draws attention to the fact that something is being replaced, thereby keeping the slurs slightly about the rug but not zooming up to hit you in the face.