Please can you add a new FME Feature Function which calculates the current date and timestamp?
You have a Timestamp() function but that requires an input string and you have a Timestamper transformer but I think it makes sense to have a Now (or Today) function similar to applications like Excel.
This means you can then test a date/time attribute against the current date/time in a Tester transformer without needing an additional transformer or use of Python.