Humans (accountants) are non-deterministic, so unsure if an LLM would be better or worse if we threw more effort at the problem.
But in general, I tend to side with the "lets leave the math to purpose built models/applications" instead of generalized LLMS. LLMs are great if you are just aiming for "good enough to get through next quarter" type results. If you need 100% accuracy, an LLM isn't going to cut it.