You can try with using a custom date range such as this:You can then use it in a segment and apply the segment in the Alert. 

You can check the following document for logic to calculate basic metrics.Calculate metrics | Adobe Analytics

There is no way to differentiate data from Data Sources in reports, including API 1.4.

There is no method to fetch segment used in scheduled reports. Though you can pull information related to segments using methods as shown here: Swagger UI (adobedocs.github.io)

Do you see the same issue without using the segment?

It would require looking into the the CSV file to troubleshoot this. Since this is a public forum, I will suggest you to open support ticket with the Analytics team and share the file so that we can review it. Also, share the report you are viewing to validate the data.

Glad to hear the issue was resolved.

You can update the configuration programmatically or using a file. See Configuration - Adobe Experience Platform Mobile SDKs (gitbook.io).

If am not mistaken 7591+1086 equals 8677 which higher than the number of visits showing in Segment C.

Please report this to Customer Care so that we can look into this error.