[kvanbrunt2]

They just discovered in real time that the machines had Microsoft SQL server installed which contained databases >>> this is similar to the Fulton County, PA assessment by Wake TSI. The SQL server software is a violation of the certification in PA.
https://drive.google.com/file/d/1VnJFxN3NdKQmcj2-8FDWMET8i__YlH7F/view?usp=sharing

[Technical]

They just discovered in real time that the machines had Microsoft SQL server installed which contained databases

You are misinterpreting the link you supplied. Here is where they are talking about software not authorized for install.

The one major area of concern with installed software is that Dominion has installed the Microsoft SQL Server Data Tools (SSDT) on the server. This software is not part of the EAC certified configuration and makes the system certification invalid.

It's no surprise that voting applications (or any applications) use SQL Server in the backend. It's the most widely used DB in corporate America.

What they are talking about is an optional component of SQL Server (SSDT - SQL Server Data Tools) that provides a front end users can use to query the DB. It's typical not to install SSDT in Production instances.

There's no problem with an application having a database to store information - what else should they do, write it to text files like in the mainframe days? Databases are more efficient and secure.

The mere presence of SSDT doesn't you give godly hacking powers, it's just a front-end tool. You can run the same queries from command line tools, or even custom applications.