The GOG copy of Temple of Elemental Evil I bought does not include the Polish version of the game, however, I do also have a physical copy on my hands. I couldn't get the patches to work for me and I can't run the Polish version through the Co8 launcher without patching the game either. Can I extract the Polish text and voice files and apply them to the English, patched version of the game so that it would work with Co8? It's just so much more convenient on modern systems as compared to running the game on it's own.
This is an old post but this information may help you. https://co8.org/community/threads/co8-mod-pack-4-0-0-and-the-polish-toee.2745/
That would be messy and bug prone for sure, unless you put in the hard work of basically porting the mod. Maybe with chat GPT?
I might try that, just one thing I don't fully understand - this thread mentions that "The game is half-English, half-Polish", but how could that happen? Did the patches change THAT much?
Try it, by all means. If I understand what you are asking, you want to do an English patched version that Co8 will recognise, but first apply your Polish text files? Sure, the worst you can do is have to reinstall. The Atari patches? Yes. The Co8 mod? Even more. The files in the Co8 mod are (with a very few exceptions for consistency) files we modded, which is why they are there - the game has various files we didn't change, that aren't included. So be prepared for all your patched Polish files to be overwritten by Co8 English ones.