Their physiology is barely diverged so their intellects are likely to remain similar. Espionage is frequently the theme of Romulan encounters, which would help keep them up to date. And if they procreate more frequently than every seven years, they might have a much larger population even with greater murderousness, with more people being advantageous for tech development.
Of course. I’m probably not the only one who thinks you like adding people to lists. Blaming your woes on the Others and treating them differently based on a mark they carry were just two of the clues.