Hi there,
You can change the localization of the system by opening a terminal and issuing the following commands
sudo apt-get update (to refresh package list)
sudo dpkg-reconfigure locales
then a menu will come up and ask to pick a "locale"
you can then scroll through all the codes to pick
Below is the code for croatian
hr_HR.UTF-8
just scroll down the list (its alphabetical) and choose that or serbian which is -
sr_CS.UTF-8 (for cyrillic) or
bs_BA.UTF-8 (for latin)
Then it should ask you which one to use for your "primary" and you can choose the ones you selected. You should be able to log out and back in and have it work, but a reboot does not hurt in my opinion also.
its not 100% accurate as not all software is configured for all languages, but its better than all english in your case I am sure
(example attached)
