There’s a fun wrinkle here: Duane didn’t simply throw out the Roman flavor. In her own account of inventing Rihannsu, she explains that she wanted a Latin-influenced language with softer sounds, imagining a people deliberately distinguishing themselves from their Vulcan ancestors. Welsh and Greek helped inspire its sound, and she even wrote a BASIC program to generate possible words. That gives the linguistic break a cultural reason instead of leaving it as a cosmic coincidence. Duane also makes an important distinction: her novels aren’t screen canon, so later television writers weren’t undoing an established on-screen answer.
Sadly, Star Trek’s screen writers never adopted Diane Duane’s cool ideas about the Romulans. Instead, we got films like Nemesis that clarified (as if anybody was asking) that sister planet Remus was filled with goblin monster people with mild (but majorly evil) telepathy. Later, NuTrek would further muddle Romulan lore in Picard with the Zhat Vash, a secretive Romulan faction whose mission is to eliminate synthetic life after interpreting an ancient warning about its dangers.
This just goes to show that the Star Trek writers have had no real idea of what to do with the Romulans for a very long time, and the fact that their name makes no sense is literally the least of these secretive aliens’ problems.
