^No, T'Ryssa's still mainly a contact specialist; like I said, we've been getting to see her do her job more often in recent books. But it's not uncommon for Starfleet officers to cross-train. On a starship, you want the crew to be able to tackle multiple jobs in the event of an emergency. You never know who'll be incapacitated/killed and who'll be left behind, so it makes sense to train the crew to do each other's jobs. In addition to the permanent transfers discussed above, we've seen a number of cases of personnel shifting between tasks as needed -- for instance, Uhura taking over navigation in "The Naked Time," Scotty and Spock operating the transporter, Sulu and Chekov going on landing parties, Mr. Leslie jumping among security and helm and engineering and maybe even medical, etc. On Voyager
we had Tom Paris double as a nurse from time to time, ops manager Harry Kim serving as de facto science officer, Neelix branch out into security, and the like.
As far as Trys goes, she came onboard as a contact specialist with some helm training, she's helped out in engineering, and there was one time when she happened to be holding the conn at a time when a crisis erupted and the senior staff was unavailable. That's not excessive compared to what we've seen from numerous other characters over the years.