Thrawn's Revenge is a large-scale mod for Empire at War: Forces of Corruption. It includes the events of the Galactic Civil War after Palpatine's death at Endor, up until the signing of the Pellaeon-Gavrisom treaty. If you own the Steam version of EaW, you will have to complete extra steps to run the mod after installation. Please see the manual for these steps.
A community-provided Polish text file for Imperial Civil War 2.2.5
"This is general Grzegorz Brzęczyszczykiewicz of the planet Chrząszczyżewoszyce in the Powiat system."
In principle, one could expect such a hack.The problem is that mododers do not have enough people who would deal with high-quality text files. Therefore, they have not only a normal translation in different languages, but also in the English texts themselves, there are only voids somewhere.