With these changes -
If the bank rejects a transaction based on risk, and it is not known whether a true match occurs (Entity involved and the beneficial owners are not known), do these transactions need to be reported?

I think you need to better define what you mean by risk. Did you run OFAC, got a hit that then upon review raised other questions or did you raise questions before running OFAC? Ultimately, if you ran OFAC, got a hit, and cleared it as a false positive, reporting would seem unnecessary in my opinion though.