internal EDT doesn’t handle column names, it uses just column numbers.
In case you have changing or changing order of columns in input files, create a help file (csv or Excel) which just includes the headers. The first thing you should do before any other action merge the file with the headers (on top of the data file) with the data file using the Stack transaction (align on “Header name”). This will bring the columns every time in an identical order and the following actions should work correctly.
Have a look to the following conversation, too: https://forum.easydatatransform.com/t/reusing-transforms-on-a-different-input-file/292/11