We apologize for the instability of composr.app and appreciate your patience. We are working on the statistics addon and trying to find an optimal way to store and render data. Unfortunately, we have yet to find a solution that can handle the traffic (and therefore, tens of millions of statistical records) of composr.app. We're working hard on one.
#2479 - CMS uses theme of zone it is accessed from
You can achieve it though via making your own menu link with :keep_theme=whatever on the end of the page-link.
The only issues there I can think of is that it sticks if you come back to the site again somehow through a link chain. Probably that's fine though.