Inserting values into array when bulk appending to a google sheet

Hi everyone - I haven't yet found a solution to this one yet, but I'm trying to add some meta data to my "Append Data to a Spreadsheet" query. For example, say I want to add the users email address to all the {{website_summary_tbl.recordUpdates}}

It seems like I should just be able to insert this data into each record of the .recordUpdates array, but ths doesn't work.

Here's the full transformer code. Any ideas?

var new_array = {{website_summary_tbl.recordUpdates}}
new_array.forEach(function(item, index) {
  data[index] = {...item, "const1": "const1 val"};
return new_array;