@Admin, the schema works now fine in case there are different orders or additional or renamed columns in the amount of files in a folder.
If you process the same files in a batch process and write the data in append mode into one file, the file structure is not adapted and entries are added into wrong columns, but with append it is not expected to change the overall columns structures. Maybe it possible to consider the changes you did now (as the from folder reading is a stack and append logic) to the append mode in batch process. Otherwise a hint can be added in documentation that append in batch mode doesn’t change the file structure form first file processed and further files with structure changes might show strange results.
Thanks for your effort to workout the solution for handling the schema issues for the new logic.
If you want the columns to be aligned by folder name on append, then you would have to do a Stack. I don’t think that is likely to change. I will see about adding something into the documentation.