I don't think this will work. I think your incoming row will find a match on your complex expression and then stop there, not looking up any further mappings (e.g., on the list tab).
I understand why you wouldn't want to put your list in the code. What you could do is have your complex expression code look up the mapping from the list.
I like the idea of having the complex expression code look up the mapping from the List. Can that be done using the existing List, and if so, how? Or would I have to move it all into a Lookup?
Thanks!
Yes it can be done from the list. If you use a lookup table there are built-in functions you can use rather than a database query although I think a database query dumping a datatable / dictionary of the list mappings or lookup table into memory would probably be better.
You can find some SQL to get you started in https://community.onestreamsoftware.com/t5/Workflow-and-Data-Integration/Transformation-rules-mappings/m-p/30478
