A: Most mods are language-agnostic. However, mods that change dialogue or subtitles may break. Install Polish pack before story mods.

For the retail DVD version (pre-GOTY):

[The Witcher 3] Which voice cast is better: English or Polish?

: Reviewers often note that the Polish voice for Geralt (Jacek Rozenek) is more expressive and nuanced compared to the famously deadpan English performance.