Yeah, after someone else -- ?Creflo? -- pointed out that the knife that MIB gave Richard (and, we're assuming, also the same knife that Dogen gave Sayid) is itself Roman, that maybe it's Jacob and MIB who are the original Romans. They may just be the latest iterations guardian/captive of the Island with Tawaret and the Smoke Monster being even older spirits. [And, for me at this point, Jack and Sawyer will be the next set of replacements.]
So if Latin is Jacob's native tongue, that would be why he taught it to the Others, and why he's the one referring to Richard as "Ricardus".