ADF resets data flow when trying to update Data Flow Script representation

Hello,

I am new to Azure Data Factory and I am trying to utilize the Data Flow Script representation to create sources and update select statements programmatically in the Data Factory browser environment. But when press "ok" after I change the script representation directly, ADF resets and removes everything in the data flow except the sources (some sources' settings are reset as well to default). Are there limitations to what you can change with the script representation? 

Info about my setup

I have multiple sources that are identical except for "Output stream name", "Manifest File" and "Entity". It would be much quicker to copy everything that is identical and change the minor differences in the script rather than manually fixing in the drag-and-drop.

Same with the select, I have to filter out and rename hundreds of columns. This would be easy to semi-automate with script representation if ADF didn't remove all select statements after I try to update.

Additional info

Changing the script seems to be no issue based on this old video ADF Data Flow Script: Intro to Copy, Paste, Snippets (youtube.com).