API and Goban Demos

Hi all again!
As some of you may remember, I succeeded in defeating the error 405 when trying to get the access token I need to let my bot (VideoKifu) connect to OGS via REST API.
My bot now connects, and is able to send some commands, such as retrieving games, any games or just its own, as well as retrieving user infos. That’s already much, indeed.
But there are some things I cannot do. I cannot send moves to any game of mine, no matter how many variations of the syntax I tried. At best, I get an error 500; at worst, I may get all other kinds of errors, both generic and specific.
Also, I cannot create a demo game, a thing I need in order to broadcast to OGS the moves of the game VideoKifu is analyzing. The documentation regarding demos is empty.

Any help will be greatly appreciated!