Consider the following tags:
potty-training: 59 questions
toilet-training: 13 questions
potty: 6 questions, 5 of which are potty training, plus a recent question about constipation
toilet: 6 questions; 1 about constipation-ish, 3 about potty training related things, 2 about toilets in public places
I suggest making potty and toilet-training synonyms for potty-training, and burninating toilet, replacing it with toilet-manners or public-toilet or something like that (it seems like the 2 public places questions are in part about manners, and there were a few others which would take that as well).
I'm aware that
toilet has a slightly complictated meaning outside of the US (inside the US it is pretty much a synonym for potty), so I'm not sure this is completely realistic. However, I think given half the questions are pretty much just potty training questions adding a second related word tag, it makes sense to change it to a different word.
I also think potty makes more sense as a potty training synonym, in part because potty-training is often entered as "potty training" and having it be a synonym would simplify that.
toilet is sufficiently different outside of the US it probably shouldn't be a synonym in my mind, though I would not object if it was.