If you want to prefix all URLs with a string like
de_DE, set that string as the store code (instead of
german) and use the "Add Store Code To URL" configuration in the answer you linked. This way, the
___from_store parameters are not necessary anymore and Magento omits them.
More info: M1: Remove "?___store=default" from the URL
If you want to use this approach, you should ask your question more specifically. By just saying "no luck" nobody can help you because we don't know what you tried and what was the problem.
But if you only want to change the URL that is used to switch stores and not all URLs, it is going to be complicated.
As long as you're okay with the language switcher always linking to the homepage you could add a
RewriteRule to your
.htaccess file like this:
RewriteRule ^de_DE$ /?___store=german
RewriteRule ^fr_FR$ /?___store=french
Then change the switcher template to use these URLs.
For the home page,
___from_store is not necessary (for an explanation see again the answer linked above)