Hey there,
I have understood your requirement, that you want a script which will read data, process it and paste back to the google sheet.
I am glad we came across your project we are a 2-year-old startup specialized in using google apps script for creating addons and automating manual workflows (among other things). We have created an add-on for Google Sheet which integrates with Gmail & Google docs to send an email blast. The input for this addon was the list of email stored in a google sheet, and a link of google docs used as an email template. With a simple click of a button, it sends the email template to the list of emails one by one via Gmail.
Another simple addon project was to send a customized proposal to clients. The user was able to select the template & product type from the dropdown in google sheets with additional parameters like a discount, client name, email, etc. The script selects the template stored in Google docs, manipulates the content to personalize it for the client and finally send an email with the proposal template as an attached PDF to the client
We have a team of developers who will be working on your project and you will be having one point of contact as me. We can also show you the proof of concept for your project before you accept this proposal from us.
Please find the screenshot of our add-on in the below link- [login to view URL]