Currently eZ publish will display the default language version of the content object - in other words, if Swedish is the default language and an English translation doesn't exist then it WILL display the Swedish one. This is a bit unfortunate and I think it will be replaced by some alternate functionality in the future (has been discussed on the internal developer mailing list). However, you could do some trick in your template: check which language it is and display something else if it is not the correct language, etc.