Language code + upgrade language 1.6.1.24

[Radek100]

Hello,

i would like to update language package in Prestashop 1.6.1.24. But administration says: Cannot connect to the PrestaShop website to get the language list. 

I downloaded tranlation manually. But if I check translation php files on FTP it is everywhere cs.php files. But downloaded files are maybe in new code form cs-CZ.php. As there are a lot of modules folder it is really hard to rename all php language files one by one. Is there any way how to handle this? My Prestashop is updated since 1.5 version where the language code should be different maybe. But this is really hard to update without access to Prestashop website + with different code of downloaded files for me.

Any ideas and advices how to solve this problem?

Thank you 
Radek