Where I have your workflow:

1. dbo.LoadPreLoadFromExcel brings the contents of the Excel into a new "load" table

2. dbo.CreateTargetTable creates a new "target" table with typed columns from data in sample_fields (this proc will not create tables with Unicode columns)

3. dbo.LoadTargetFromFile copies data from "load" table created into "target" table

4. dbo.CreateProcessTable creates a new "process" table

5. dbo.LoadProcessfromTarget copies data from "target" to "process" table

I am assuming you sent me the definition for the "process" table because it has NVARCHAR columns and dbo.CreateTargetTable does not know how to create NVARCHAR columns in the "target" table. I think your problem is in the creation of the "target" table, i.e. in step 2 above. Can you please send the table definitions for the "load", "target" and "process" tables for this project, scripted out of SSMS by right-clicking the each and selecting "Script Table As" > "Create" as opposed to a copy/paste from the grid?