We need the confirmation from Appsheet team if our understanding is correct or not. @prithpal @Dan_Bahir
Google spreadsheet add-on , Appsheet Events, is capable of detecting the change of value in the sheet, when the user is open Google spreadsheet app and directly interacting this app. Add-on just notice when you change the values when you are on the spreadsheet. When you close the google spreadsheet (as app), then this Add-on will not do the job.
If you make a change to the spreadsheet with Add-on from external service like your task app, then Spreadsheet add-on have no idea, as the event is happening to trigger the automation, as it is not getting through google sheet as application.
Confusion is coming from here.
From app creator point of view, we use spreadsheet as data source, so googlesheet is kinda of back-end service in this respects. This is true. But when it comes to Appsheet Events add-on, this is working as installed tool to google sheet as app, so it is not a backend servce but front end service (working on the clients devices)