That calculus as a modern field wasn't established until the 1600's does not mean the Romans only had geometry. That's not how technology works. It doesn't fit neatly into containers defined by modern thought. They likely developed what they needed and thought nothing of calling it something else because their purpose for it was different. For example Calculus is often called the study of change, not something the Romans were super interested in. Unlike the Greeks who were figuring out astronomy math. If you want to see how far they were before things started falling apart you'd have to get a historian to tell you what they even considered the mathematical fields to be and look at how they used it.