While you can click into and edit the criteria of an Audience that is tied to an automated push notification, clicking Save will throw an error:
This will prevent any inadvertent issues.
If you need to make an edit to the Audience, you will need to duplicate the audience or create a new one, then apply the new changes.
An automated push message that has already sent to users cannot be modified. To apply the new audience to the push message, the original push message will need to be duplicated to create a new message and then original message would need to be archived.