Hello all,
I had the same problem with the application manager. I follow the step but I did not want to change my region settings, since I have them customized.
What I did try is the following:
- Removed the protuguese language (5th posistion from the top) form "languange"
- relaunch finder --> open application manager.
=> RESULT: language of the application manager was now the language of the language on the 5th position (chineese)
- I moved british english to the 5th position
=> RESULT: the language of the application manager is english.
Hope that help to fix the problem on OS X.
Regards Marcus