Czech translation is obviously created by some autotranslate. "Site" (and web site) has two meanings in czech - "website" and "house". Piwik is using "house" in all translations. I changed it to better translation.
Thanks for your pull request. Unfortunately we will not merge any pull requests for translation files. We are using an external tool to manage our translations (http://translations.piwik.org). Please register there and make future changes only there. We are automatically merging all translations from there to git from time to time. As you have done quite many changes, I'll try to import your changes there. But it would be nice if you could have a look there aswell, as I don't speek the language.
Thank you, I will register there and I am going to correct some more.