Hi!
I'm not sure if this forum is still alive or not, but I have prepared the full Polish translation for the current version of CPG (1.6.26).
My translation is mostly based on Vurmil's earlier (outdated) translation. I added all new sentences in the new translation. Compared to the old translation, I also changed names of some options to make them more understandable.
In the attachment you will find the polish.php file (zipped).