Sorry for the slow reply. In response to your question:
While adding this kind of functionality is theoretically possible, there is currently no mechanism for restricting a given user to a subset of the data for a given app. Using your example, if a user is restricted to a specific app, he/she will still be able to see all the data for that app (e.g. data for all countries). You are the first person to request this functionality, so it is not something that is even on our current roadmap for future releases.
As far as the User-Restriction plug-in for the Enterprise Edition, this restricts specific Countly modules at the user level (e.g. you may turn off push notifications or crash reporting for a specific user or users).
Let us know if you have any further questions/comments.