Everything in the mod is working as of this post. I saw other posts saying the event changing doesn't work but it needs to be set up a certain way for everything to work.
To make the Rallycross work on Rally, you must do the following:
The Event must be set to Single Race. (On the event, go to Event Options, then Event Settings, and set it to Single Race)
When you do this though, it changes the vehicle class you would've selected early when selecting the track, so in the same Event Settings, you can set the class here. But because this is setting it in Rallycross settings, if you wanted Rally cars, make sure to have the "Change Cars" selected, but if you wanted the Rallycross cars, have it not selected.
Basically, you should just select the track for the event, then adjust everything else like vehicle class and race settings in the Event Settings.
If you're doing Rallycross on a Rally track with other players, they will need the mod as well to make sure the Recover Vehicle/track resetting works properly. They would need the mod running, and have the checkbox at the bottom checked.
Here's a video with the setup working with other players:
https://youtu.be/86DBWGYSTO0