The problem is that when i go to Settings -> Customizations, it does not allow me to make any changes to existing entites, neither it allows me to create a new, custom one.
It just displays a simple message: WARNING: Solution and Publisher Options are not available since your language does not match system base language.
I tried googleing and searching for an option to find this base system language, thus far no succes. How can i achieve the possibility to edit and create new custom entities.