I don't think spreadsheets are a good way to program data transformations at all. Data transformations are inherently a pipeline/function abstraction, and even non-technical users understand that. Spreadsheets don't offer a good way to decompose a data transformation process and inspect each step for correctness. This alone makes them prone to calculation errors. Also, tables are an afterthought to spreadsheets, therefore even trivial joins are always a pain in Excel.
I have a good practical experience with building visual pipeline-based data transformation tools [1] for non-technical users and they have been a success.