You’re more than welcome to say it’s impossible 
All I know for a fact is that I create a command in Streamlabs ChatBot that will have the chatbot say whatever I want when I say !bananas, for example.
When the program detects me saying something, it posts a custom message directly into the chat. Perhaps it’s this point that it’s doing something behind the scenes, such as your unsupported API end point.
When it sees "!Bananas ", it posts "/raid " or whatever else I ask it to post. This in turn successfully triggers the raid. Same works for /host and /unhost.
Twitch used to have the ability to trigger raids and follow people using bots, but they removed that feature for new applications, leaving it in place for those that were created before its removal. New applications do not have access to it (found it on the Twitch API documentation).
My theory was that these older programs, that I’ve seen are still using code from 2 years ago, are still able to do it.
In any case, I’ve found a way around it, and it turns out bots indeed can start a raid through a little effort 