Proposed by Tim as an enhancement for FP-Akka on the [Proposed Features] page:

Preservation of original data values in records passed between actors.

Data validation actors in the QC workflow currently overwrite the original values in the record fields for which they propose updated values.
Although comments added as new fields into the records record the original values, these are not as easily read programmatically, e.g. by a user of the report spreadsheet.
Overwriting values also means that downstream actors cannot access the original values and propose alternative values based on the originals.