region: All input sources should be selectable irrespective of which locales have been generated
The GUI in g-c-c for adding input sources shows a selection of sources depending on which locales have been generated. This makes little sense, since any input source can be used irrespective of which locales are present, and causes user confusion.
Example III: User couldn't find the Belgian keyboard layouts
It does make sense IMO to make use of generated locales for the suggestions in the first window, but no input sources should be completely hidden due to the absence of a particular locale.
Please reconsider the design in this respect.