Hi Alex !
Yes, about one point you are right, my translation was very buggy, i fixed it, but it didn´t solved the problem.
I solved in an additional way:
No matter, if the english language is installed, ALL desired languages must be installed, too !
For example: My site is running with three languages: German, English and Indonesian. Actually i assumed i just only need the german and the indonesian language packages only, english is already installed.... WRONG !
For everyone who already has experiences with building up a multilanguage site will understand me immediately: the default language (here:english) is just only used, if no other language is aviable, anyway if the construction of the site is ready for 3 languages (articles, modules,....)
My solution: you must upload EACH desired language (in my case: german, indonesian AND english, additional to the already installed default language "English"), then the automatic switch of the languages will work....
This thread can be marked as solved...