Hello,

So, if i have well understood, you want to do 2 things :
- User propose events in Frontend only in a selected category
- User see in calendar ony events in their category

Is it right ?

In fact, today not access option for category yet (it is in my todo list, but don't know when i will work on this...)

What could be done today, is (with special settings and tips ) is to allow users of one user group to add events in one category (not multiple, so need only one category by usergroups).
In the same way, possible to set menu as well as modules access to the user groups access levels, and on module per category and set for this access level.

But, i'm not sure this could be a solution for you now, if you need for some users to be able to see and propose events in more than 1 category...

Regards,
Cyril

Note: of course, when access on category will be added, the logic will be available for Submit an Event form too.