Tl;dr - display the record count in MagicETL on each step of the last successful run of the ETL.
Detail:
I often spend quite some time diagnosing and fixing ETLs. In larger ETLs, it can be very onerous to determine whether a record with an expected behaviour makes it through the entire flow to the end to validate the ETL.
I've had some experience with Alteryx which has a useful feature where it displays on the ETL builder the record counts in each step of the ETL.
Here is a clip from YouTube showcasing this: https://youtu.be/8-rRytmZlvI?si=2cKjucmKN3AzU9Ny&t=1324
