Hi Chris,
Thank you so much for your response!
I was definitely feeding in the wrong formatting for the DateColumn type.
These were the pieces I was missing:
var date = Utilities.formatDate(values[i][6], “GMT-4”, “YYYY-MM-dd”);
“colvals”: JSON.stringify({“text”:values[i][1],“date”:{“date”:date}})
With that in place, everything is submitting properly!
Thanks again!