Re: Why No Romulan Ships?
I doubt they'd have had the knowledge to do that though, given the secrecy of Pressman's plan. Or the resources, the research capacity etc.
The Borg assimiliated Romulans. I'm sure at least a few of them understood how to build and/or maintain a cloaking device. I don't know that they'd have knoweldge of something like a phasing cloak because that was classified, but a basic cloaking device should have been known throughout the Collective. That Janeway didn't at least ask Seven about it is surprising.
"He clapped his captain—his friend—on the shoulder. Yes, this man was very much like James Kirk, in all the ways that mattered." --Christopher L. Bennett-- Star Trek: Mere Anarachy, The Darkness Drops Again