I donno, I think translations do a good enough job most of the time. No it's not the same, but appreciating foreign literature is more about knowing the culture, saysing, folklore etc. than purely speaking the language, I think.
Tho I hear the Witcher english translations are really bad. And Sapkowski is a really witty writer who plays with the Polish language a lot too, so I think it would indeed lose a bit in translation. But as I said above, you'd really need to know Polish history and folk tales to really appreciate it.