In the settings module for Regional Formats, you display formats as Regions, which means little to the user.  Common use case "I want 24-hour time format" require hunting about until you find a Region that happens to use both your language and a 24-hour format.

While I recognize that the values (locales) being selected are those that are actually set (to configure Qt), the drop-downs should show what the effect would be, for instance, for the Time Sub-format:

English Canada (en_CA) 3:44 PM
United Kingdom - UK English (en_UK) 15:44

would at least make it obvious from the drop-down what you are selecting as a format.

This doesn't address the desires of those who, for instance, speak Albanian yet want a 12-hour clock format, of course.

Reproducible: Always

Steps to Reproduce:
1. Go to Regional Format Page
2. Attempt to Configure an en_CA region with a 24-hour time format


Actual Results:  
Have to find the English section and then use arrow-keys to switch the values while scanning the sample text at the bottom to check the formats.

Expected Results:  
Be able to see at a glance the sub-format being selected.