what you are saying doesnt make sense.

You dont need a backend workflow to make an API call. Make the api call from the front end workflow.. The front end workflow will then schedule an API call to a backend workflow with the results from the external API call.

you will want to create a backend API Workflow because that is the only way to operate on a list of things. The front end workflow will call the external api. Then you call your backend workflow with the list of things from your external API call.

Your backend workflow will operate on a single item from the list. When you call it using schedule an API workflow on a list of things, bubble will call your backend workflow once for each item in the list of things from the API call. Note that bubble will run all the calls to your backend workflow in parallel so the list may be added to the database out of order. You need to use recursion if you want to serialize the list.

Your backend workflow will create a single item in your database and in that moment you can decide to send a toast notification for that attempt if there is some problem (why would the item not be created in the database?). You do not need to return 200/400

This youtube video describes how to do this. The first half is not that relevant so this should start in the part of the video that is relevant to your question