thanks for report, found the problem. It will be fixed later today with RC2 release. Although the log shows that the installer was trying to install EET using en_US TLK files. BG2:EE doesn't support Polish language officially yet, but installer checks TLK files presence anyway. Did you have dialog.tlk file in lang/pl_PL/ directory when you started the installation? (It's distributed on Beamdog forums). Btw. later today I will also update this mod to properly show Polish language from the options screen (patch 2.x force us to also patch BG:EE LUA to add new language and the mod was released for patch 1.3). Unfortunately viader is missing in action, so the mirror linked in this topic won't be updated for some time.
The only way to install polish text and dubbing in BG2:EE is described by TartamPuan in this topic: https://forums.beamdog.com/discussion/23812/bg2-ee-kwestia-wersji-polskiej-oraz-jej-instalacja/p21
I wanted to do it later, since i didn't know this won't prevent EET installation. Now i first installed translation by this method and then started EET installation, which this time finished ("due to errors").
EDIT: Just launched the game and translation is completly broken. UI is in english, first movie (Zbudowana na szczycie skał....) has no sound, NPCs have randomly no voices, english voices or polish voices and most entries and dialogues has "Invalid value":
