Magento 1.9 Extensions – Extension Installer Issue (Magento Connect Manager)

Try this may be its use full to you. It solved my problem.
Go to downloader/lib/Mage/Archive/Helper/File/Gz.php in your Magento directory
and replace

$this->_fileHandler = @gzopen($this->_filePath, $mode); 

with

$this->_fileHandler = @gzopen64($this->_filePath, $mode);

I think the simplest solution here will be to create 301 redirects for your pages in different languages in the url rewrites management admin section.
Something like this:

For DE store view redirect from bags.html to taschen.html.
For EN store view redirect from taschen.html to bags.html.

Do the same for all the other combinations.
this way, when you switch from domain.com/en/bags.html to DE you it will points to a page that does not exist domain.com/de/bags.html but that will do a 301 redirect to domain.com/de/taschen.html.
I know that there are a lot of redirects to create, but I can recommend you this extension. All you need to do is to provide the url keys for each store view and it will create automatically the redirects.

But if you don't like this approach, you may need to rewrite the Mage_Core_Model_Store::getCurrentUrl method to look in the url_rewrites table and get the url for each language. But this may cause performance issues and it is not a bullet proof solution, because it will not work for cms pages or other custom page.

I don't have a full working solution for this, but I can give you some pointers.
Look in the core_url_rewrites table for a target path matching the $requestString var in the method mentioned above for the store that should generate the url and append to the target path value the query string.