I've found simple solution!
This method changes main/home/base adress/domain and leads to same URL on other adress/domain. It's also simple installed, just one HTML/JS widget :)
What you should do before:
1. Create two blogs in two different languages.
2. Go to Settings->Search options and make a link to your own site in "page not found code" just in case :) it can look like:
There is nothing in this link, please continue on <a href="http://olesku.pl">Olesku.pl</a>.
Put your adress instead of mine ;)
document.write ("<a href=" + window.location.protocol + "//" + "theotherlanguageadress.com" + window.location.pathname + ">the other language name</a>");
Put adress of the second-language-blog in theotherlanguageadress.com and name of language used in another blog in the other language name.