Copying a workbook to a new format workbook

I hate it to be the bearer of bad news, but the best way to copy over data verbatim like the way you described is ctrl + c and then ctrl + v.

Correct. These language models are meant to summarize information and generate (relatively) novel content based on what data its fed. It is working as intended.

Are you using the API? Perhaps a simple RAG setup that pulls up a needed file is what you need here. If not, I’m unsure if using a language model fits your purpose very well in this case.