This thought just occurred to me as I glanced over a notification that came in on another thread ("...there does not seem to be a way of seeing exactly which layout is in action for a page, even by inspecting the code." Source)
What about a new little icon in the admin menu that either links to a separate page or has a little dropdown info pane with details about the current page you are viewing?

For example, all in one place, info (and potentially links to edit/adjust) about the:
- Layout used on this page
- Theme
- Content type
- etc.
That may be overkill but thought I'd throw it out there to see what people thought.
Recent comments
There is a Drupal 7 contrib module that "lets the administrator see all administration pages in her preferred language" and which could be ported to Backdrop: https://www.drupal.org/project/...
Allow admin to select admin language seperate from front end language (multilingual)
@stpaultim – You're right: my approach affects also the main menu. I guess, because menus are also considered as user interface (not as content). @findlabnet – If I didn't miss anything,...
Allow admin to select admin language seperate from front end language (multilingual)
Go to the account edit of the desired user. On the horizontal tab below "Region and Language," select "English" or another language. WFM.
Allow admin to select admin language seperate from front end language (multilingual)