I did what you wrote. I also changed Revit.ini file to set proper language but nothing happened. What is funny:
"DefaultTemplate=Stavební šablona=C:\ProgramData\Autodesk\RVT 2013\Templates\France\Construction-DefaultFRAFRA.r
Can somebody tell me if it realy works and what shoud I do to make it happen?
you should download proper language pack from subscription center, not from autodesk webpage. And check if it is for suite or architecture/structure/mep only.
Could you provide more details regarding your problem installing the Polish language pack? Is there an error message and when do you see the error message; during the install setup, at the end of the installation process or when attmepting to launch the product? Hopefully with a bit more information, we can get the language pack installed and running on your system.
Autodesk Revit QA