Whenever a function name or something gets renamed, assets referencing that function throws an error during deserialization, naturally. Paired with the refactoring tool, this is super awesome! However, there is no easy way to find what graph assets are actually causing the issues. The simplest solution would be to simply name the relevant graph asset in the error text to allow for easier debugging!
If you have the Graph Console open, then all validation errors (like this) will point to the related node and clicking the log in the Graph Console will open the related graph and focus that node automatically. Does this not work for you? 🙂