Whenever I post via the API, I tested it in Postman and it sends the right things to the right category.
However, when I more or less copy+paste the same thing with an http POST (via JavaScript), I get everything right…EXCEPT the category (which I thought was the easiest part):
Ahhhh apparently error 422 is rate-limiting. The category “number” IS actually “text” (a string). Making bot account admin seemed to do the trick for the limiting (…but why do I have to make it an ADMIN to edit rate limiting? Seems a bit of a dramatic upgrade for such) and “15” as the category as a string.