I think you have a misunderstanding of the types of things that LLMs are good at. Yes you're 100% right that they can't do math. Yet they're quite proficient at basic coding. Most Excel work is similar to basic coding so I think this is an area where they might actually be pretty well suited.
My concern would be more with how to check the work (ie, make sure that the formulas are correct and no columns are missed) because Excel hides all that. Unlike code, there's no easy way to generate the diff of a spreadsheet or rely on Git history. But that's different from the concerns that you have.
My concern would be more with how to check the work (ie, make sure that the formulas are correct and no columns are missed) because Excel hides all that. Unlike code, there's no easy way to generate the diff of a spreadsheet or rely on Git history. But that's different from the concerns that you have.