Unless you changed the name of your context (or it is localized to something else), in your sidebar, click the resources tab. There is a bar near the top with a globe icon “Website” and then a plus in a circle and the “refresh” icon. If you right click on that, it shows you a bunch of context options.
Click on edit context, and in the new window click Context Settings and click “Create New” button.
in this case your key would be evxEventsPage and evxEventPage, and their values would be the corresponding id’s
It doesn’t sound like you need to change the namespace from core, but in the future some extras/plugins do use a specific namespace (for example, Ace editor settings). Maybe someone with more experience with that plugin will jump in and let us know