[fny]

There's a project from Microsoft Research that's really interesting which does just that:

https://www.microsoft.com/en-us/research/publication/melford...

[nanoamp]

It looks like it's not quite the same thing, in that it identifies Excel values that should be formulae. It could be used in a pipeline with spreadsheets extracted by ML/OCR to reverse-engineer formulae though, which is an interesting prospect.