The API is a constantly evolving thing, and for things which have been specifically documented to work a certain way then Twitch are good at responding to either intentional changes to that, or bugs which can be fixed. For things that aren’t documented or guaranteed to work a certain way then things can change without such responses from Twitch.
As a 3rd party developer it’s best practices to work within the bounds of the documented API if you have strict uptime requirements to keep in a production app, the more assumptions you make, or undocumented endpoints you use, the more at risk your app is to use in a production environment.
Anyway, this has gone offtopic now so if you’re unhappy with Twitch’s response, feel free to submit a support ticket.