When accessing admin/structure/display-modes/view at the end of each entity type there's a link for adding a new view mode. Here are some examples:
Add new Custom block view mode
Add new Comment view mode
Add new Taxonomy term view mode
The problem is that the string used to create this output and also used for translation is: Add new %label @entity-type which looking above @entity-type should be 'Custom block', 'Comment' and 'Taxonomy term' not 'view mode' and %label should be 'view mode' not the actual entity types.
This is confusing when translating the UI and should be an easy fix.