Well, the problem was found within the name of the language file. I changed brazilian.php into Brazilian.php and a second later the extension worked perfectly also in portugues.
I will make it short, with the English and German language configuration it worked perfectly. And the result is unbelievable. The usage is very easy.
I only advice to use a template with white background. My first template had a dark gray background which fit terribly to the RealEstateManager (without doing changes on it).
If you look for a easy to use Real Estate component, give it a try. I may have had some problems, but I solved them without giving at least a try to the support team. In the past I used a different extension which was not for free, which still don't work with Joomla 2.5 yet and which was much more complicated to customize.