wikipedia article on spreadsheets mentions that in complex spreadsheets changes propagate as the spirit moves them (at least as far as the typical human mind can tell) but does not go into details about how people deal with that. The Comparison of spreadsheet software - Wikipedia article mentions a few tools that sound like spreadsheet-oriented diff but gives no details.
First of all, does anybody even care? Are there lots of Excel spreadsheets out there with enough formulas for this to be an issue? Or is this a real issue but let’s say not for Excel but for some other Spreadsheet X system that is used by the type of people who like complex spreadsheets?
Second, what is the start of the art on tools, whether standalone or built into existing spreadsheets, for figuring out “what happens if I change these couple of cells”? Is diffing sufficient for this? Have their been attempts and/or would it make any sense to try to capture and display to the user the process of propagation of changes through the spreadsheet formula graph?