I, like /u/CommodoreCoCo, don't understand what you mean by "a monopoly on Roman numerals." I feel I should also add something in reference to this remark:

no one refers to the Latin language as Roman

The Latin language is not called the Roman language because it was not the Roman language. Latin was spoken by the Latins in Italy, who inhabited Latium. The inhabitants of Rome had many close ties with Latium of course, but they were not Latins, only speaking the same language. The city of Rome from earliest times was influenced by a great many different people, most notably Latins, Sabines, and Etruscans, and as the Romans themselves recognized they kept traditions from all those groups. The Romans themselves recognized that they spoke the lingua Latina, and that the language was derived from Latium

Rome did not have a monopoly on Roman numerals

Could you clarify what you mean by this? Roman numerals, as we know them, were first used by Romans, adapting local (Etruscan) traditions into the Latin script. Other places have used them, but they still started in Rome. Additionally, the Latin language hardly has a "monopoloy" on Roman numerals, so I myself do not see what would change.