Another reason why it’s better to change ‘not archived’ into ‘active’ is
because ‘active’ is the functional name of this field in the filter list in list view.
For the rest, it’s just a better en_US way of saying it.
Template arch can contrains "groups" attributes on the html tag but can't have group_id setted. (to allow a cache per template and lang instead of a cache per template, user and lang)
When event is created/finished/cancelled, event registration page shows same error message.
It shouldn't be same. So changed error message for finished/cancelled event.